diff --git a/cache.go b/caches/lruCacher.go
similarity index 59%
rename from cache.go
rename to caches/lruCacher.go
index e1ccc0d1..6f851922 100644
--- a/cache.go
+++ b/caches/lruCacher.go
@@ -1,107 +1,21 @@
-package xorm
+//LRUCacher implements Cacher according to LRU algorithm
+package caches
 
 import (
 	"container/list"
-	"errors"
 	"fmt"
-	"strconv"
-	"strings"
 	"sync"
 	"time"
+
+	"github.com/lunny/xorm/core"
 )
 
-const (
-	// default cache expired time
-	CacheExpired = 60 * time.Minute
-	// not use now
-	CacheMaxMemory = 256
-	// evey ten minutes to clear all expired nodes
-	CacheGcInterval = 10 * time.Minute
-	// each time when gc to removed max nodes
-	CacheGcMaxRemoved = 20
-)
-
-// CacheStore is a interface to store cache
-type CacheStore interface {
-	Put(key, value interface{}) error
-	Get(key interface{}) (interface{}, error)
-	Del(key interface{}) error
-}
-
-// MemoryStore implements CacheStore provide local machine
-// memory store
-type MemoryStore struct {
-	store map[interface{}]interface{}
-	mutex sync.RWMutex
-}
-
-func NewMemoryStore() *MemoryStore {
-	return &MemoryStore{store: make(map[interface{}]interface{})}
-}
-
-func (s *MemoryStore) Put(key, value interface{}) error {
-	s.mutex.Lock()
-	defer s.mutex.Unlock()
-	s.store[key] = value
-	return nil
-}
-
-func (s *MemoryStore) Get(key interface{}) (interface{}, error) {
-	s.mutex.RLock()
-	defer s.mutex.RUnlock()
-	if v, ok := s.store[key]; ok {
-		return v, nil
-	}
-
-	return nil, ErrNotExist
-}
-
-func (s *MemoryStore) Del(key interface{}) error {
-	s.mutex.Lock()
-	defer s.mutex.Unlock()
-	delete(s.store, key)
-	return nil
-}
-
-// Cacher is an interface to provide cache
-type Cacher interface {
-	GetIds(tableName, sql string) interface{}
-	GetBean(tableName string, id int64) interface{}
-	PutIds(tableName, sql string, ids interface{})
-	PutBean(tableName string, id int64, obj interface{})
-	DelIds(tableName, sql string)
-	DelBean(tableName string, id int64)
-	ClearIds(tableName string)
-	ClearBeans(tableName string)
-}
-
-type idNode struct {
-	tbName    string
-	id        int64
-	lastVisit time.Time
-}
-
-type sqlNode struct {
-	tbName    string
-	sql       string
-	lastVisit time.Time
-}
-
-func newIdNode(tbName string, id int64) *idNode {
-	return &idNode{tbName, id, time.Now()}
-}
-
-func newSqlNode(tbName, sql string) *sqlNode {
-	return &sqlNode{tbName, sql, time.Now()}
-}
-
-// LRUCacher implements Cacher according to LRU algorithm
 type LRUCacher struct {
 	idList     *list.List
 	sqlList    *list.List
-	idIndex    map[string]map[interface{}]*list.Element
-	sqlIndex   map[string]map[interface{}]*list.Element
-	store      CacheStore
+	idIndex    map[string]map[string]*list.Element
+	sqlIndex   map[string]map[string]*list.Element
+	store      core.CacheStore
 	Max        int
 	mutex      sync.Mutex
 	Expired    time.Duration
@@ -109,25 +23,17 @@ type LRUCacher struct {
 	GcInterval time.Duration
 }
 
-func newLRUCacher(store CacheStore, expired time.Duration, maxSize int, max int) *LRUCacher {
+func NewLRUCacher(store core.CacheStore, expired time.Duration, maxSize int, max int) *LRUCacher {
 	cacher := &LRUCacher{store: store, idList: list.New(),
 		sqlList: list.New(), Expired: expired, maxSize: maxSize,
-		GcInterval: CacheGcInterval, Max: max,
-		sqlIndex: make(map[string]map[interface{}]*list.Element),
-		idIndex:  make(map[string]map[interface{}]*list.Element),
+		GcInterval: core.CacheGcInterval, Max: max,
+		sqlIndex: make(map[string]map[string]*list.Element),
+		idIndex:  make(map[string]map[string]*list.Element),
 	}
 	cacher.RunGC()
 	return cacher
 }
 
-func NewLRUCacher(store CacheStore, max int) *LRUCacher {
-	return newLRUCacher(store, CacheExpired, CacheMaxMemory, max)
-}
-
-func NewLRUCacher2(store CacheStore, expired time.Duration, max int) *LRUCacher {
-	return newLRUCacher(store, expired, 0, max)
-}
-
 //func NewLRUCacher3(store CacheStore, expired time.Duration, maxSize int) *LRUCacher {
 //    return newLRUCacher(store, expired, maxSize, 0)
 //}
@@ -148,7 +54,7 @@ func (m *LRUCacher) GC() {
 	defer m.mutex.Unlock()
 	var removedNum int
 	for e := m.idList.Front(); e != nil; {
-		if removedNum <= CacheGcMaxRemoved &&
+		if removedNum <= core.CacheGcMaxRemoved &&
 			time.Now().Sub(e.Value.(*idNode).lastVisit) > m.Expired {
 			removedNum++
 			next := e.Next()
@@ -164,7 +70,7 @@ func (m *LRUCacher) GC() {
 
 	removedNum = 0
 	for e := m.sqlList.Front(); e != nil; {
-		if removedNum <= CacheGcMaxRemoved &&
+		if removedNum <= core.CacheGcMaxRemoved &&
 			time.Now().Sub(e.Value.(*sqlNode).lastVisit) > m.Expired {
 			removedNum++
 			next := e.Next()
@@ -184,7 +90,7 @@ func (m *LRUCacher) GetIds(tableName, sql string) interface{} {
 	m.mutex.Lock()
 	defer m.mutex.Unlock()
 	if _, ok := m.sqlIndex[tableName]; !ok {
-		m.sqlIndex[tableName] = make(map[interface{}]*list.Element)
+		m.sqlIndex[tableName] = make(map[string]*list.Element)
 	}
 	if v, err := m.store.Get(sql); err == nil {
 		if el, ok := m.sqlIndex[tableName][sql]; !ok {
@@ -209,11 +115,11 @@ func (m *LRUCacher) GetIds(tableName, sql string) interface{} {
 }
 
 // Get bean according tableName and id from cache
-func (m *LRUCacher) GetBean(tableName string, id int64) interface{} {
+func (m *LRUCacher) GetBean(tableName string, id string) interface{} {
 	m.mutex.Lock()
 	defer m.mutex.Unlock()
 	if _, ok := m.idIndex[tableName]; !ok {
-		m.idIndex[tableName] = make(map[interface{}]*list.Element)
+		m.idIndex[tableName] = make(map[string]*list.Element)
 	}
 	tid := genId(tableName, id)
 	if v, err := m.store.Get(tid); err == nil {
@@ -248,7 +154,7 @@ func (m *LRUCacher) clearIds(tableName string) {
 			m.store.Del(sql)
 		}
 	}
-	m.sqlIndex[tableName] = make(map[interface{}]*list.Element)
+	m.sqlIndex[tableName] = make(map[string]*list.Element)
 }
 
 func (m *LRUCacher) ClearIds(tableName string) {
@@ -261,11 +167,11 @@ func (m *LRUCacher) clearBeans(tableName string) {
 	if tis, ok := m.idIndex[tableName]; ok {
 		for id, v := range tis {
 			m.idList.Remove(v)
-			tid := genId(tableName, id.(int64))
+			tid := genId(tableName, id)
 			m.store.Del(tid)
 		}
 	}
-	m.idIndex[tableName] = make(map[interface{}]*list.Element)
+	m.idIndex[tableName] = make(map[string]*list.Element)
 }
 
 func (m *LRUCacher) ClearBeans(tableName string) {
@@ -278,7 +184,7 @@ func (m *LRUCacher) PutIds(tableName, sql string, ids interface{}) {
 	m.mutex.Lock()
 	defer m.mutex.Unlock()
 	if _, ok := m.sqlIndex[tableName]; !ok {
-		m.sqlIndex[tableName] = make(map[interface{}]*list.Element)
+		m.sqlIndex[tableName] = make(map[string]*list.Element)
 	}
 	if el, ok := m.sqlIndex[tableName][sql]; !ok {
 		el = m.sqlList.PushBack(newSqlNode(tableName, sql))
@@ -294,7 +200,7 @@ func (m *LRUCacher) PutIds(tableName, sql string, ids interface{}) {
 	}
 }
 
-func (m *LRUCacher) PutBean(tableName string, id int64, obj interface{}) {
+func (m *LRUCacher) PutBean(tableName string, id string, obj interface{}) {
 	m.mutex.Lock()
 	defer m.mutex.Unlock()
 	var el *list.Element
@@ -331,7 +237,7 @@ func (m *LRUCacher) DelIds(tableName, sql string) {
 	m.delIds(tableName, sql)
 }
 
-func (m *LRUCacher) delBean(tableName string, id int64) {
+func (m *LRUCacher) delBean(tableName string, id string) {
 	tid := genId(tableName, id)
 	if el, ok := m.idIndex[tableName][id]; ok {
 		delete(m.idIndex[tableName], id)
@@ -341,55 +247,36 @@ func (m *LRUCacher) delBean(tableName string, id int64) {
 	m.store.Del(tid)
 }
 
-func (m *LRUCacher) DelBean(tableName string, id int64) {
+func (m *LRUCacher) DelBean(tableName string, id string) {
 	m.mutex.Lock()
 	defer m.mutex.Unlock()
 	m.delBean(tableName, id)
 }
 
-func encodeIds(ids []int64) (s string) {
-	s = "["
-	for _, id := range ids {
-		s += fmt.Sprintf("%v,", id)
-	}
-	s = s[:len(s)-1] + "]"
-	return
+type idNode struct {
+	tbName    string
+	id        string
+	lastVisit time.Time
 }
 
-func decodeIds(s string) []int64 {
-	res := make([]int64, 0)
-	if len(s) >= 2 {
-		ss := strings.Split(s[1:len(s)-1], ",")
-		for _, s := range ss {
-			i, err := strconv.ParseInt(s, 10, 64)
-			if err != nil {
-				return res
-			}
-			res = append(res, i)
-		}
-	}
-	return res
-}
-
-func getCacheSql(m Cacher, tableName, sql string, args interface{}) ([]int64, error) {
-	bytes := m.GetIds(tableName, genSqlKey(sql, args))
-	if bytes == nil {
-		return nil, errors.New("Not Exist")
-	}
-	objs := decodeIds(bytes.(string))
-	return objs, nil
-}
-
-func putCacheSql(m Cacher, ids []int64, tableName, sql string, args interface{}) error {
-	bytes := encodeIds(ids)
-	m.PutIds(tableName, genSqlKey(sql, args), bytes)
-	return nil
+type sqlNode struct {
+	tbName    string
+	sql       string
+	lastVisit time.Time
 }
 
 func genSqlKey(sql string, args interface{}) string {
 	return fmt.Sprintf("%v-%v", sql, args)
 }
 
-func genId(prefix string, id int64) string {
+func genId(prefix string, id string) string {
 	return fmt.Sprintf("%v-%v", prefix, id)
 }
+
+func newIdNode(tbName string, id string) *idNode {
+	return &idNode{tbName, id, time.Now()}
+}
+
+func newSqlNode(tbName, sql string) *sqlNode {
+	return &sqlNode{tbName, sql, time.Now()}
+}
diff --git a/caches/memoryStore.go b/caches/memoryStore.go
new file mode 100644
index 00000000..8bbb6b99
--- /dev/null
+++ b/caches/memoryStore.go
@@ -0,0 +1,49 @@
+// MemoryStore implements CacheStore provide local machine
+package caches
+
+import (
+	"errors"
+	"sync"
+
+	"github.com/lunny/xorm/core"
+)
+
+var (
+	ErrNotExist = errors.New("key not exist")
+)
+
+var _ core.CacheStore = NewMemoryStore()
+
+// memory store
+type MemoryStore struct {
+	store map[interface{}]interface{}
+	mutex sync.RWMutex
+}
+
+func NewMemoryStore() *MemoryStore {
+	return &MemoryStore{store: make(map[interface{}]interface{})}
+}
+
+func (s *MemoryStore) Put(key string, value interface{}) error {
+	s.mutex.Lock()
+	defer s.mutex.Unlock()
+	s.store[key] = value
+	return nil
+}
+
+func (s *MemoryStore) Get(key string) (interface{}, error) {
+	s.mutex.RLock()
+	defer s.mutex.RUnlock()
+	if v, ok := s.store[key]; ok {
+		return v, nil
+	}
+
+	return nil, ErrNotExist
+}
+
+func (s *MemoryStore) Del(key string) error {
+	s.mutex.Lock()
+	defer s.mutex.Unlock()
+	delete(s.store, key)
+	return nil
+}
diff --git a/core/cache.go b/core/cache.go
new file mode 100644
index 00000000..bedd22a7
--- /dev/null
+++ b/core/cache.go
@@ -0,0 +1,77 @@
+package core
+
+import (
+	"encoding/json"
+	"errors"
+	"fmt"
+	"time"
+)
+
+const (
+	// default cache expired time
+	CacheExpired = 60 * time.Minute
+	// not use now
+	CacheMaxMemory = 256
+	// evey ten minutes to clear all expired nodes
+	CacheGcInterval = 10 * time.Minute
+	// each time when gc to removed max nodes
+	CacheGcMaxRemoved = 20
+)
+
+// CacheStore is a interface to store cache
+type CacheStore interface {
+	// key is primary key or composite primary key or unique key's value
+	// value is struct's pointer
+	// key format : <tablename>-p-<pk1>-<pk2>...
+	Put(key string, value interface{}) error
+	Get(key string) (interface{}, error)
+	Del(key string) error
+}
+
+// Cacher is an interface to provide cache
+// id format : u-<pk1>-<pk2>...
+type Cacher interface {
+	GetIds(tableName, sql string) interface{}
+	GetBean(tableName string, id string) interface{}
+	PutIds(tableName, sql string, ids interface{})
+	PutBean(tableName string, id string, obj interface{})
+	DelIds(tableName, sql string)
+	DelBean(tableName string, id string)
+	ClearIds(tableName string)
+	ClearBeans(tableName string)
+}
+
+func encodeIds(ids []PK) (string, error) {
+	b, err := json.Marshal(ids)
+	if err != nil {
+		return "", err
+	}
+	return string(b), nil
+}
+
+func decodeIds(s string) ([]PK, error) {
+	pks := make([]PK, 0)
+	err := json.Unmarshal([]byte(s), &pks)
+	return pks, err
+}
+
+func GetCacheSql(m Cacher, tableName, sql string, args interface{}) ([]PK, error) {
+	bytes := m.GetIds(tableName, GenSqlKey(sql, args))
+	if bytes == nil {
+		return nil, errors.New("Not Exist")
+	}
+	return decodeIds(bytes.(string))
+}
+
+func PutCacheSql(m Cacher, ids []PK, tableName, sql string, args interface{}) error {
+	bytes, err := encodeIds(ids)
+	if err != nil {
+		return err
+	}
+	m.PutIds(tableName, GenSqlKey(sql, args), bytes)
+	return nil
+}
+
+func GenSqlKey(sql string, args interface{}) string {
+	return fmt.Sprintf("%v-%v", sql, args)
+}
diff --git a/core/db.go b/core/db.go
index 9249c2a8..3f96b343 100644
--- a/core/db.go
+++ b/core/db.go
@@ -2,43 +2,138 @@ package core
 
 import (
 	"database/sql"
+	"errors"
 	"reflect"
 )
 
 type DB struct {
 	*sql.DB
+	Mapper IMapper
 }
 
 func Open(driverName, dataSourceName string) (*DB, error) {
 	db, err := sql.Open(driverName, dataSourceName)
-	return &DB{db}, err
+	return &DB{db, &SnakeMapper{}}, err
 }
 
 func (db *DB) Query(query string, args ...interface{}) (*Rows, error) {
 	rows, err := db.DB.Query(query, args...)
-	return &Rows{rows}, err
+	return &Rows{rows, db.Mapper}, err
 }
 
 type Rows struct {
 	*sql.Rows
+	Mapper IMapper
 }
 
-func (rs *Rows) Scan(dest ...interface{}) error {
-	newDest := make([]interface{}, 0)
-	for _, s := range dest {
-		vv := reflect.ValueOf(s)
-		switch vv.Kind() {
-		case reflect.Ptr:
-			vvv := vv.Elem()
-			if vvv.Kind() == reflect.Struct {
-				for j := 0; j < vvv.NumField(); j++ {
-					newDest = append(newDest, vvv.FieldByIndex([]int{j}).Addr().Interface())
-				}
-			} else {
-				newDest = append(newDest, s)
-			}
+// scan data to a struct's pointer according field index
+func (rs *Rows) ScanStruct(dest interface{}) error {
+	vv := reflect.ValueOf(dest)
+	if vv.Kind() != reflect.Ptr || vv.Elem().Kind() != reflect.Struct {
+		return errors.New("dest should be a struct's pointer")
+	}
+
+	vvv := vv.Elem()
+	newDest := make([]interface{}, vvv.NumField())
+
+	for j := 0; j < vvv.NumField(); j++ {
+		newDest[j] = vvv.Field(j).Addr().Interface()
+	}
+
+	return rs.Rows.Scan(newDest...)
+}
+
+// scan data to a struct's pointer according field name
+func (rs *Rows) ScanStruct2(dest interface{}) error {
+	vv := reflect.ValueOf(dest)
+	if vv.Kind() != reflect.Ptr || vv.Elem().Kind() != reflect.Struct {
+		return errors.New("dest should be a struct's pointer")
+	}
+
+	cols, err := rs.Columns()
+	if err != nil {
+		return err
+	}
+
+	vvv := vv.Elem()
+	newDest := make([]interface{}, len(cols))
+
+	for j, name := range cols {
+		f := vvv.FieldByName(rs.Mapper.Table2Obj(name))
+		if f.IsValid() {
+			newDest[j] = f.Addr().Interface()
+		} else {
+			var v interface{}
+			newDest[j] = &v
 		}
 	}
 
 	return rs.Rows.Scan(newDest...)
 }
+
+// scan data to a slice's pointer, slice's length should equal to columns' number
+func (rs *Rows) ScanSlice(dest interface{}) error {
+	vv := reflect.ValueOf(dest)
+	if vv.Kind() != reflect.Ptr || vv.Elem().Kind() != reflect.Slice {
+		return errors.New("dest should be a slice's pointer")
+	}
+
+	vvv := vv.Elem()
+	cols, err := rs.Columns()
+	if err != nil {
+		return err
+	}
+
+	newDest := make([]interface{}, len(cols))
+
+	for j := 0; j < len(cols); j++ {
+		if j >= vvv.Len() {
+			newDest[j] = reflect.New(vvv.Type().Elem()).Interface()
+		} else {
+			newDest[j] = vvv.Index(j).Addr().Interface()
+		}
+	}
+
+	err = rs.Rows.Scan(newDest...)
+	if err != nil {
+		return err
+	}
+
+	for i, _ := range cols {
+		vvv = reflect.Append(vvv, reflect.ValueOf(newDest[i]).Elem())
+	}
+	return nil
+}
+
+// scan data to a map's pointer
+func (rs *Rows) ScanMap(dest interface{}) error {
+	vv := reflect.ValueOf(dest)
+	if vv.Kind() != reflect.Ptr || vv.Elem().Kind() != reflect.Map {
+		return errors.New("dest should be a map's pointer")
+	}
+
+	cols, err := rs.Columns()
+	if err != nil {
+		return err
+	}
+
+	newDest := make([]interface{}, len(cols))
+	vvv := vv.Elem()
+
+	for i, _ := range cols {
+		v := reflect.New(vvv.Type().Elem())
+		newDest[i] = v.Interface()
+	}
+
+	err = rs.Rows.Scan(newDest...)
+	if err != nil {
+		return err
+	}
+
+	for i, name := range cols {
+		vname := reflect.ValueOf(name)
+		vvv.SetMapIndex(vname, reflect.ValueOf(newDest[i]).Elem())
+	}
+
+	return nil
+}
diff --git a/core/db_test.go b/core/db_test.go
index 8894bd17..26f2e04d 100644
--- a/core/db_test.go
+++ b/core/db_test.go
@@ -2,7 +2,9 @@ package core
 
 import (
 	"fmt"
+	"os"
 	"testing"
+	"time"
 
 	_ "github.com/mattn/go-sqlite3"
 )
@@ -20,7 +22,8 @@ type User struct {
 	NickName string
 }
 
-func TestQuery(t *testing.T) {
+func TestOriQuery(t *testing.T) {
+	os.Remove("./test.db")
 	db, err := Open("sqlite3", "./test.db")
 	if err != nil {
 		t.Error(err)
@@ -31,23 +34,197 @@ func TestQuery(t *testing.T) {
 		t.Error(err)
 	}
 
-	_, err = db.Exec("insert into user (name, title, age, alias, nick_name) values (?,?,?,?,?)",
-		"xlw", "tester", 1.2, "lunny", "lunny xiao")
+	for i := 0; i < 50; i++ {
+		_, err = db.Exec("insert into user (name, title, age, alias, nick_name) values (?,?,?,?,?)",
+			"xlw", "tester", 1.2, "lunny", "lunny xiao")
+		if err != nil {
+			t.Error(err)
+		}
+	}
+
+	rows, err := db.Query("select * from user")
 	if err != nil {
 		t.Error(err)
 	}
+	defer rows.Close()
+
+	start := time.Now()
+
+	for rows.Next() {
+		var Id int64
+		var Name, Title, Alias, NickName string
+		var Age float32
+		err = rows.Scan(&Id, &Name, &Title, &Age, &Alias, &NickName)
+		if err != nil {
+			t.Error(err)
+		}
+		fmt.Println(Id, Name, Title, Age, Alias, NickName)
+	}
+
+	fmt.Println("ori ------", time.Now().Sub(start), "ns")
+}
+
+func TestStructQuery(t *testing.T) {
+	os.Remove("./test.db")
+	db, err := Open("sqlite3", "./test.db")
+	if err != nil {
+		t.Error(err)
+	}
+
+	_, err = db.Exec(createTableSqlite3)
+	if err != nil {
+		t.Error(err)
+	}
+
+	for i := 0; i < 50; i++ {
+		_, err = db.Exec("insert into user (name, title, age, alias, nick_name) values (?,?,?,?,?)",
+			"xlw", "tester", 1.2, "lunny", "lunny xiao")
+		if err != nil {
+			t.Error(err)
+		}
+	}
+
+	rows, err := db.Query("select * from user")
+	if err != nil {
+		t.Error(err)
+	}
+	defer rows.Close()
+	start := time.Now()
+
+	for rows.Next() {
+		var user User
+		err = rows.ScanStruct(&user)
+		if err != nil {
+			t.Error(err)
+		}
+		fmt.Println(user)
+	}
+	fmt.Println("struct ------", time.Now().Sub(start))
+}
+
+func TestStruct2Query(t *testing.T) {
+	os.Remove("./test.db")
+	db, err := Open("sqlite3", "./test.db")
+	if err != nil {
+		t.Error(err)
+	}
+
+	_, err = db.Exec(createTableSqlite3)
+	if err != nil {
+		t.Error(err)
+	}
+
+	for i := 0; i < 50; i++ {
+		_, err = db.Exec("insert into user (name, title, age, alias, nick_name) values (?,?,?,?,?)",
+			"xlw", "tester", 1.2, "lunny", "lunny xiao")
+		if err != nil {
+			t.Error(err)
+		}
+	}
+
+	db.Mapper = &SnakeMapper{}
+
+	rows, err := db.Query("select * from user")
+	if err != nil {
+		t.Error(err)
+	}
+	defer rows.Close()
+	start := time.Now()
+
+	for rows.Next() {
+		var user User
+		err = rows.ScanStruct2(&user)
+		if err != nil {
+			t.Error(err)
+		}
+		fmt.Println(user)
+	}
+	fmt.Println("struct2 ------", time.Now().Sub(start))
+}
+
+func TestSliceQuery(t *testing.T) {
+	os.Remove("./test.db")
+	db, err := Open("sqlite3", "./test.db")
+	if err != nil {
+		t.Error(err)
+	}
+
+	_, err = db.Exec(createTableSqlite3)
+	if err != nil {
+		t.Error(err)
+	}
+
+	for i := 0; i < 50; i++ {
+		_, err = db.Exec("insert into user (name, title, age, alias, nick_name) values (?,?,?,?,?)",
+			"xlw", "tester", 1.2, "lunny", "lunny xiao")
+		if err != nil {
+			t.Error(err)
+		}
+	}
 
 	rows, err := db.Query("select * from user")
 	if err != nil {
 		t.Error(err)
 	}
 
+	defer rows.Close()
+
+	cols, err := rows.Columns()
+	if err != nil {
+		t.Error(err)
+	}
+
+	start := time.Now()
+
 	for rows.Next() {
-		var user User
-		err = rows.Scan(&user)
+		slice := make([]interface{}, len(cols))
+		err = rows.ScanSlice(&slice)
 		if err != nil {
 			t.Error(err)
 		}
-		fmt.Println(user)
+		fmt.Println(slice)
 	}
+
+	fmt.Println("slice ------", time.Now().Sub(start))
+}
+
+func TestMapQuery(t *testing.T) {
+	os.Remove("./test.db")
+	db, err := Open("sqlite3", "./test.db")
+	if err != nil {
+		t.Error(err)
+	}
+
+	_, err = db.Exec(createTableSqlite3)
+	if err != nil {
+		t.Error(err)
+	}
+
+	for i := 0; i < 50; i++ {
+		_, err = db.Exec("insert into user (name, title, age, alias, nick_name) values (?,?,?,?,?)",
+			"xlw", "tester", 1.2, "lunny", "lunny xiao")
+		if err != nil {
+			t.Error(err)
+		}
+	}
+
+	rows, err := db.Query("select * from user")
+	if err != nil {
+		t.Error(err)
+	}
+
+	defer rows.Close()
+
+	start := time.Now()
+
+	for rows.Next() {
+		m := make(map[string]interface{})
+		err = rows.ScanMap(&m)
+		if err != nil {
+			t.Error(err)
+		}
+		fmt.Println(m)
+	}
+
+	fmt.Println("map ------", time.Now().Sub(start))
 }
diff --git a/core/dialect.go b/core/dialect.go
index fd7a483e..ecba0844 100644
--- a/core/dialect.go
+++ b/core/dialect.go
@@ -107,7 +107,7 @@ func (b *Base) CreateTableSql(table *Table, tableName, storeEngine, charset stri
 
 	if len(pkList) > 1 {
 		sql += "PRIMARY KEY ( "
-		sql += strings.Join(pkList, ",")
+		sql += b.Quote(strings.Join(pkList, b.Quote(",")))
 		sql += " ), "
 	}
 
diff --git a/mapper.go b/core/mapper.go
similarity index 99%
rename from mapper.go
rename to core/mapper.go
index 2e9c220a..0011dde5 100644
--- a/mapper.go
+++ b/core/mapper.go
@@ -1,4 +1,4 @@
-package xorm
+package core
 
 import (
 	"strings"
diff --git a/core/pk.go b/core/pk.go
new file mode 100644
index 00000000..61d1371e
--- /dev/null
+++ b/core/pk.go
@@ -0,0 +1,25 @@
+package core
+
+import (
+	"encoding/json"
+)
+
+type PK []interface{}
+
+func NewPK(pks ...interface{}) *PK {
+	p := PK(pks)
+	return &p
+}
+
+func (p *PK) ToString() (string, error) {
+	bs, err := json.Marshal(*p)
+	if err != nil {
+		return "", nil
+	}
+
+	return string(bs), nil
+}
+
+func (p *PK) FromString(content string) error {
+	return json.Unmarshal([]byte(content), p)
+}
diff --git a/core/pk_test.go b/core/pk_test.go
new file mode 100644
index 00000000..5245e574
--- /dev/null
+++ b/core/pk_test.go
@@ -0,0 +1,22 @@
+package core
+
+import (
+	"fmt"
+	"testing"
+)
+
+func TestPK(t *testing.T) {
+	p := NewPK(1, 3, "string")
+	str, err := p.ToString()
+	if err != nil {
+		t.Error(err)
+	}
+	fmt.Println(str)
+
+	s := &PK{}
+	err = s.FromString(str)
+	if err != nil {
+		t.Error(err)
+	}
+	fmt.Println(s)
+}
diff --git a/dialects/postgres.go b/dialects/postgres.go
index dbf9ca09..8a37d117 100644
--- a/dialects/postgres.go
+++ b/dialects/postgres.go
@@ -26,7 +26,7 @@ func (db *postgres) SqlType(c *Column) string {
 	switch t := c.SQLType.Name; t {
 	case TinyInt:
 		res = SmallInt
-
+		return res
 	case MediumInt, Int, Integer:
 		if c.IsAutoIncrement {
 			return Serial
diff --git a/engine.go b/engine.go
index a6509828..dc3fd637 100644
--- a/engine.go
+++ b/engine.go
@@ -16,13 +16,11 @@ import (
 	"github.com/lunny/xorm/core"
 )
 
-type PK []interface{}
-
 // Engine is the major struct of xorm, it means a database manager.
 // Commonly, an application only need one engine
 type Engine struct {
-	ColumnMapper   IMapper
-	TableMapper    IMapper
+	ColumnMapper   core.IMapper
+	TableMapper    core.IMapper
 	TagIdentifier  string
 	DriverName     string
 	DataSourceName string
@@ -37,20 +35,20 @@ type Engine struct {
 	Pool         IConnectPool
 	Filters      []core.Filter
 	Logger       io.Writer
-	Cacher       Cacher
-	tableCachers map[reflect.Type]Cacher
+	Cacher       core.Cacher
+	tableCachers map[reflect.Type]core.Cacher
 }
 
-func (engine *Engine) SetMapper(mapper IMapper) {
+func (engine *Engine) SetMapper(mapper core.IMapper) {
 	engine.SetTableMapper(mapper)
 	engine.SetColumnMapper(mapper)
 }
 
-func (engine *Engine) SetTableMapper(mapper IMapper) {
+func (engine *Engine) SetTableMapper(mapper core.IMapper) {
 	engine.TableMapper = mapper
 }
 
-func (engine *Engine) SetColumnMapper(mapper IMapper) {
+func (engine *Engine) SetColumnMapper(mapper core.IMapper) {
 	engine.ColumnMapper = mapper
 }
 
@@ -100,7 +98,7 @@ func (engine *Engine) SetMaxIdleConns(conns int) {
 }
 
 // SetDefaltCacher set the default cacher. Xorm's default not enable cacher.
-func (engine *Engine) SetDefaultCacher(cacher Cacher) {
+func (engine *Engine) SetDefaultCacher(cacher core.Cacher) {
 	engine.Cacher = cacher
 }
 
@@ -119,7 +117,7 @@ func (engine *Engine) NoCascade() *Session {
 }
 
 // Set a table use a special cacher
-func (engine *Engine) MapCacher(bean interface{}, cacher Cacher) {
+func (engine *Engine) MapCacher(bean interface{}, cacher core.Cacher) {
 	t := rType(bean)
 	engine.autoMapType(t)
 	engine.tableCachers[t] = cacher
@@ -409,7 +407,7 @@ func (engine *Engine) mapType(t reflect.Type) *core.Table {
 	return mappingTable(t, engine.TableMapper, engine.ColumnMapper, engine.dialect, engine.TagIdentifier)
 }
 
-func mappingTable(t reflect.Type, tableMapper IMapper, colMapper IMapper, dialect core.Dialect, tagId string) *core.Table {
+func mappingTable(t reflect.Type, tableMapper core.IMapper, colMapper core.IMapper, dialect core.Dialect, tagId string) *core.Table {
 	table := core.NewEmptyTable()
 	table.Name = tableMapper.Obj2Table(t.Name())
 	table.Type = t
@@ -517,6 +515,7 @@ func mappingTable(t reflect.Type, tableMapper IMapper, colMapper IMapper, dialec
 				if col.Length2 == 0 {
 					col.Length2 = col.SQLType.DefaultLength2
 				}
+				fmt.Println("======", col)
 				if col.Name == "" {
 					col.Name = colMapper.Obj2Table(t.Field(i).Name)
 				}
@@ -613,6 +612,24 @@ func (engine *Engine) IsTableExist(bean interface{}) (bool, error) {
 	return has, err
 }
 
+func (engine *Engine) IdOf(bean interface{}) core.PK {
+	table := engine.autoMap(bean)
+	v := reflect.Indirect(reflect.ValueOf(bean))
+	pk := make([]interface{}, len(table.PrimaryKeys))
+	for i, col := range table.PKColumns() {
+		pkField := v.FieldByName(col.FieldName)
+		switch pkField.Kind() {
+		case reflect.String:
+			pk[i] = pkField.String()
+		case reflect.Int, reflect.Int8, reflect.Int16, reflect.Int32, reflect.Int64:
+			pk[i] = pkField.Int()
+		case reflect.Uint, reflect.Uint8, reflect.Uint16, reflect.Uint32, reflect.Uint64:
+			pk[i] = pkField.Uint()
+		}
+	}
+	return core.PK(pk)
+}
+
 // create indexes
 func (engine *Engine) CreateIndexes(bean interface{}) error {
 	session := engine.NewSession()
@@ -627,7 +644,7 @@ func (engine *Engine) CreateUniques(bean interface{}) error {
 	return session.CreateUniques(bean)
 }
 
-func (engine *Engine) getCacher(t reflect.Type) Cacher {
+func (engine *Engine) getCacher(t reflect.Type) core.Cacher {
 	if cacher, ok := engine.tableCachers[t]; ok {
 		return cacher
 	}
@@ -635,7 +652,7 @@ func (engine *Engine) getCacher(t reflect.Type) Cacher {
 }
 
 // If enabled cache, clear the cache bean
-func (engine *Engine) ClearCacheBean(bean interface{}, id int64) error {
+func (engine *Engine) ClearCacheBean(bean interface{}, id string) error {
 	t := rType(bean)
 	if t.Kind() != reflect.Struct {
 		return errors.New("error params")
diff --git a/session.go b/session.go
index a983237b..382370c7 100644
--- a/session.go
+++ b/session.go
@@ -588,6 +588,7 @@ func (statement *Statement) convertIdSql(sqlStr string) string {
 			if len(sqls) != 2 {
 				return ""
 			}
+			fmt.Println("-----", col)
 			newsql := fmt.Sprintf("SELECT %v.%v FROM %v", statement.Engine.Quote(statement.TableName()),
 				statement.Engine.Quote(col.Name), sqls[1])
 			return newsql
@@ -612,14 +613,14 @@ func (session *Session) cacheGet(bean interface{}, sqlStr string, args ...interf
 	cacher := session.Engine.getCacher(session.Statement.RefTable.Type)
 	tableName := session.Statement.TableName()
 	session.Engine.LogDebug("[xorm:cacheGet] find sql:", newsql, args)
-	ids, err := getCacheSql(cacher, tableName, newsql, args)
+	ids, err := core.GetCacheSql(cacher, tableName, newsql, args)
 	if err != nil {
 		resultsSlice, err := session.query(newsql, args...)
 		if err != nil {
 			return false, err
 		}
 		session.Engine.LogDebug("[xorm:cacheGet] query ids:", resultsSlice)
-		ids = make([]int64, 0)
+		ids = make([]core.PK, 0)
 		if len(resultsSlice) > 0 {
 			data := resultsSlice[0]
 			var id int64
@@ -631,10 +632,10 @@ func (session *Session) cacheGet(bean interface{}, sqlStr string, args ...interf
 					return false, err
 				}
 			}
-			ids = append(ids, id)
+			ids = append(ids, core.PK{id})
 		}
 		session.Engine.LogDebug("[xorm:cacheGet] cache ids:", newsql, ids)
-		err = putCacheSql(cacher, ids, tableName, newsql, args)
+		err = core.PutCacheSql(cacher, ids, tableName, newsql, args)
 		if err != nil {
 			return false, err
 		}
@@ -646,7 +647,11 @@ func (session *Session) cacheGet(bean interface{}, sqlStr string, args ...interf
 		structValue := reflect.Indirect(reflect.ValueOf(bean))
 		id := ids[0]
 		session.Engine.LogDebug("[xorm:cacheGet] get bean:", tableName, id)
-		cacheBean := cacher.GetBean(tableName, id)
+		sid, err := id.ToString()
+		if err != nil {
+			return false, err
+		}
+		cacheBean := cacher.GetBean(tableName, sid)
 		if cacheBean == nil {
 			newSession := session.Engine.NewSession()
 			defer newSession.Close()
@@ -664,7 +669,7 @@ func (session *Session) cacheGet(bean interface{}, sqlStr string, args ...interf
 			}
 
 			session.Engine.LogDebug("[xorm:cacheGet] cache bean:", tableName, id, cacheBean)
-			cacher.PutBean(tableName, id, cacheBean)
+			cacher.PutBean(tableName, sid, cacheBean)
 		} else {
 			session.Engine.LogDebug("[xorm:cacheGet] cached bean:", tableName, id, cacheBean)
 			has = true
@@ -695,7 +700,7 @@ func (session *Session) cacheFind(t reflect.Type, sqlStr string, rowsSlicePtr in
 
 	table := session.Statement.RefTable
 	cacher := session.Engine.getCacher(t)
-	ids, err := getCacheSql(cacher, session.Statement.TableName(), newsql, args)
+	ids, err := core.GetCacheSql(cacher, session.Statement.TableName(), newsql, args)
 	if err != nil {
 		//session.Engine.LogError(err)
 		resultsSlice, err := session.query(newsql, args...)
@@ -709,7 +714,7 @@ func (session *Session) cacheFind(t reflect.Type, sqlStr string, rowsSlicePtr in
 		}
 
 		tableName := session.Statement.TableName()
-		ids = make([]int64, 0)
+		ids = make([]core.PK, 0)
 		if len(resultsSlice) > 0 {
 			for _, data := range resultsSlice {
 				//fmt.Println(data)
@@ -722,11 +727,11 @@ func (session *Session) cacheFind(t reflect.Type, sqlStr string, rowsSlicePtr in
 						return err
 					}
 				}
-				ids = append(ids, id)
+				ids = append(ids, core.PK{id})
 			}
 		}
 		session.Engine.LogDebug("[xorm:cacheFind] cache ids:", ids, tableName, newsql, args)
-		err = putCacheSql(cacher, ids, tableName, newsql, args)
+		err = core.PutCacheSql(cacher, ids, tableName, newsql, args)
 		if err != nil {
 			return err
 		}
@@ -735,34 +740,32 @@ func (session *Session) cacheFind(t reflect.Type, sqlStr string, rowsSlicePtr in
 	}
 
 	sliceValue := reflect.Indirect(reflect.ValueOf(rowsSlicePtr))
-	pkFieldName := session.Statement.RefTable.PKColumns()[0].FieldName
+	//pkFieldName := session.Statement.RefTable.PKColumns()[0].FieldName
 
-	ididxes := make(map[int64]int)
-	var ides []interface{} = make([]interface{}, 0)
+	ididxes := make(map[string]int)
+	var ides []core.PK = make([]core.PK, 0)
 	var temps []interface{} = make([]interface{}, len(ids))
 	tableName := session.Statement.TableName()
 	for idx, id := range ids {
-		bean := cacher.GetBean(tableName, id)
+		sid, err := id.ToString()
+		if err != nil {
+			return err
+		}
+		bean := cacher.GetBean(tableName, sid)
 		if bean == nil {
 			ides = append(ides, id)
-			ididxes[id] = idx
+			ididxes[sid] = idx
 		} else {
 			session.Engine.LogDebug("[xorm:cacheFind] cached bean:", tableName, id, bean)
 
-			pkField := reflect.Indirect(reflect.ValueOf(bean)).FieldByName(pkFieldName)
-
-			var sid int64
-			switch pkField.Type().Kind() {
-			case reflect.Int32, reflect.Int, reflect.Int64:
-				sid = pkField.Int()
-			case reflect.Uint, reflect.Uint32, reflect.Uint64:
-				sid = int64(pkField.Uint())
-			default:
-				return ErrCacheFailed
+			pk := session.Engine.IdOf(bean)
+			xid, err := pk.ToString()
+			if err != nil {
+				return err
 			}
 
-			if sid != id {
-				session.Engine.LogError("[xorm:cacheFind] error cache", id, sid, bean)
+			if sid != xid {
+				session.Engine.LogError("[xorm:cacheFind] error cache", xid, sid, bean)
 				return ErrCacheFailed
 			}
 			temps[idx] = bean
@@ -777,7 +780,19 @@ func (session *Session) cacheFind(t reflect.Type, sqlStr string, rowsSlicePtr in
 		beans := slices.Interface()
 		//beans := reflect.New(sliceValue.Type()).Interface()
 		//err = newSession.In("(id)", ides...).OrderBy(session.Statement.OrderStr).NoCache().Find(beans)
-		err = newSession.In("(id)", ides...).NoCache().Find(beans)
+		ff := make([][]interface{}, len(table.PrimaryKeys))
+		for i, _ := range table.PrimaryKeys {
+			ff[i] = make([]interface{}, 0)
+		}
+		for _, ie := range ides {
+			for i, _ := range table.PrimaryKeys {
+				ff[i] = append(ff[i], ie[i])
+			}
+		}
+		for i, name := range table.PrimaryKeys {
+			newSession.In(name, ff[i]...)
+		}
+		err = newSession.NoCache().Find(beans)
 		if err != nil {
 			return err
 		}
@@ -789,12 +804,16 @@ func (session *Session) cacheFind(t reflect.Type, sqlStr string, rowsSlicePtr in
 				rv = rv.Addr()
 			}
 			bean := rv.Interface()
-			id := reflect.Indirect(reflect.ValueOf(bean)).FieldByName(pkFieldName).Int()
+			id := session.Engine.IdOf(bean)
+			sid, err := id.ToString()
+			if err != nil {
+				return err
+			}
 			//bean := vs.Index(i).Addr().Interface()
-			temps[ididxes[id]] = bean
+			temps[ididxes[sid]] = bean
 			//temps[idxes[i]] = bean
 			session.Engine.LogDebug("[xorm:cacheFind] cache bean:", tableName, id, bean)
-			cacher.PutBean(tableName, id, bean)
+			cacher.PutBean(tableName, sid, bean)
 		}
 	}
 
@@ -811,16 +830,21 @@ func (session *Session) cacheFind(t reflect.Type, sqlStr string, rowsSlicePtr in
 				sliceValue.Set(reflect.Append(sliceValue, reflect.Indirect(reflect.ValueOf(bean))))
 			}
 		} else if sliceValue.Kind() == reflect.Map {
-			var key int64
+			var key core.PK
 			if table.PrimaryKeys[0] != "" {
 				key = ids[j]
-			} else {
-				key = int64(j)
 			}
-			if t.Kind() == reflect.Ptr {
-				sliceValue.SetMapIndex(reflect.ValueOf(key), reflect.ValueOf(bean))
-			} else {
-				sliceValue.SetMapIndex(reflect.ValueOf(key), reflect.Indirect(reflect.ValueOf(bean)))
+
+			if len(key) == 1 {
+				ikey, err := strconv.ParseInt(fmt.Sprintf("%v", key[0]), 10, 64)
+				if err != nil {
+					return err
+				}
+				if t.Kind() == reflect.Ptr {
+					sliceValue.SetMapIndex(reflect.ValueOf(ikey), reflect.ValueOf(bean))
+				} else {
+					sliceValue.SetMapIndex(reflect.ValueOf(ikey), reflect.Indirect(reflect.ValueOf(bean)))
+				}
 			}
 		}
 		/*} else {
@@ -2762,7 +2786,7 @@ func (session *Session) cacheUpdate(sqlStr string, args ...interface{}) error {
 	cacher := session.Engine.getCacher(table.Type)
 	tableName := session.Statement.TableName()
 	session.Engine.LogDebug("[xorm:cacheUpdate] get cache sql", newsql, args[nStart:])
-	ids, err := getCacheSql(cacher, tableName, newsql, args[nStart:])
+	ids, err := core.GetCacheSql(cacher, tableName, newsql, args[nStart:])
 	if err != nil {
 		resultsSlice, err := session.query(newsql, args[nStart:]...)
 		if err != nil {
@@ -2770,7 +2794,7 @@ func (session *Session) cacheUpdate(sqlStr string, args ...interface{}) error {
 		}
 		session.Engine.LogDebug("[xorm:cacheUpdate] find updated id", resultsSlice)
 
-		ids = make([]int64, 0)
+		ids = make([]core.PK, 0)
 		if len(resultsSlice) > 0 {
 			for _, data := range resultsSlice {
 				var id int64
@@ -2782,7 +2806,7 @@ func (session *Session) cacheUpdate(sqlStr string, args ...interface{}) error {
 						return err
 					}
 				}
-				ids = append(ids, id)
+				ids = append(ids, core.PK{id})
 			}
 		}
 	} /*else {
@@ -2791,7 +2815,11 @@ func (session *Session) cacheUpdate(sqlStr string, args ...interface{}) error {
 	}*/
 
 	for _, id := range ids {
-		if bean := cacher.GetBean(tableName, id); bean != nil {
+		sid, err := id.ToString()
+		if err != nil {
+			return err
+		}
+		if bean := cacher.GetBean(tableName, sid); bean != nil {
 			sqls := splitNNoCase(sqlStr, "where", 2)
 			if len(sqls) == 0 || len(sqls) > 2 {
 				return ErrCacheFailed
@@ -2834,7 +2862,7 @@ func (session *Session) cacheUpdate(sqlStr string, args ...interface{}) error {
 			}
 
 			session.Engine.LogDebug("[xorm:cacheUpdate] update cache", tableName, id, bean)
-			cacher.PutBean(tableName, id, bean)
+			cacher.PutBean(tableName, sid, bean)
 		}
 	}
 	session.Engine.LogDebug("[xorm:cacheUpdate] clear cached table sql:", tableName)
@@ -3047,13 +3075,13 @@ func (session *Session) cacheDelete(sqlStr string, args ...interface{}) error {
 
 	cacher := session.Engine.getCacher(session.Statement.RefTable.Type)
 	tableName := session.Statement.TableName()
-	ids, err := getCacheSql(cacher, tableName, newsql, args)
+	ids, err := core.GetCacheSql(cacher, tableName, newsql, args)
 	if err != nil {
 		resultsSlice, err := session.query(newsql, args...)
 		if err != nil {
 			return err
 		}
-		ids = make([]int64, 0)
+		ids = make([]core.PK, 0)
 		if len(resultsSlice) > 0 {
 			for _, data := range resultsSlice {
 				var id int64
@@ -3065,7 +3093,7 @@ func (session *Session) cacheDelete(sqlStr string, args ...interface{}) error {
 						return err
 					}
 				}
-				ids = append(ids, id)
+				ids = append(ids, core.PK{id})
 			}
 		}
 	} /*else {
@@ -3075,7 +3103,11 @@ func (session *Session) cacheDelete(sqlStr string, args ...interface{}) error {
 
 	for _, id := range ids {
 		session.Engine.LogDebug("[xorm:cacheDelete] delete cache obj", tableName, id)
-		cacher.DelBean(tableName, id)
+		sid, err := id.ToString()
+		if err != nil {
+			return err
+		}
+		cacher.DelBean(tableName, sid)
 	}
 	session.Engine.LogDebug("[xorm:cacheDelete] clear cache table", tableName)
 	cacher.ClearIds(tableName)
diff --git a/statement.go b/statement.go
index 8b5ff430..23cb0591 100644
--- a/statement.go
+++ b/statement.go
@@ -24,7 +24,7 @@ type Statement struct {
 	Start         int
 	LimitN        int
 	WhereStr      string
-	IdParam       *PK
+	IdParam       *core.PK
 	Params        []interface{}
 	OrderStr      string
 	JoinStr       string
@@ -421,24 +421,28 @@ func (statement *Statement) TableName() string {
 	return ""
 }
 
+var (
+	ptrPkType = reflect.TypeOf(&core.PK{})
+	pkType    = reflect.TypeOf(core.PK{})
+)
+
 // Generate "where id = ? " statment or for composite key "where key1 = ? and key2 = ?"
 func (statement *Statement) Id(id interface{}) *Statement {
-
 	idValue := reflect.ValueOf(id)
 	idType := reflect.TypeOf(idValue.Interface())
 
 	switch idType {
-	case reflect.TypeOf(&PK{}):
-		if pkPtr, ok := (id).(*PK); ok {
+	case ptrPkType:
+		if pkPtr, ok := (id).(*core.PK); ok {
 			statement.IdParam = pkPtr
 		}
-	case reflect.TypeOf(PK{}):
-		if pk, ok := (id).(PK); ok {
+	case pkType:
+		if pk, ok := (id).(core.PK); ok {
 			statement.IdParam = &pk
 		}
 	default:
 		// TODO treat as int primitve for now, need to handle type check
-		statement.IdParam = &PK{id}
+		statement.IdParam = &core.PK{id}
 
 		// !nashtsai! REVIEW although it will be user's mistake if called Id() twice with
 		// different value and Id should be PK's field name, however, at this stage probably
@@ -789,31 +793,12 @@ func (statement *Statement) genSelectSql(columnStr string) (a string) {
 }
 
 func (statement *Statement) processIdParam() {
-
 	if statement.IdParam != nil {
-		i := 0
-		columns := statement.RefTable.ColumnsSeq()
-		colCnt := len(columns)
-		for _, elem := range *(statement.IdParam) {
-			for ; i < colCnt; i++ {
-				colName := columns[i]
-				col := statement.RefTable.GetColumn(colName)
-				if col.IsPrimaryKey {
-					statement.And(fmt.Sprintf("%v=?", col.Name), elem)
-					i++
-					break
-				}
-			}
-		}
-
-		// !nashtsai! REVIEW what if statement.IdParam has insufficient pk item? handle it
-		// as empty string for now, so this will result sql exec failed instead of unexpected
-		// false update/delete
-		for ; i < colCnt; i++ {
-			colName := columns[i]
-			col := statement.RefTable.GetColumn(colName)
-			if col.IsPrimaryKey {
-				statement.And(fmt.Sprintf("%v=?", col.Name), "")
+		for i, col := range statement.RefTable.PKColumns() {
+			if i < len(*(statement.IdParam)) {
+				statement.And(fmt.Sprintf("%v=?", statement.Engine.Quote(col.Name)), (*(statement.IdParam))[i])
+			} else {
+				statement.And(fmt.Sprintf("%v=?", statement.Engine.Quote(col.Name)), "")
 			}
 		}
 	}
diff --git a/tests/base_test.go b/tests/base_test.go
index cf12066a..26d6cf9c 100644
--- a/tests/base_test.go
+++ b/tests/base_test.go
@@ -1,4 +1,4 @@
-package xorm
+package tests
 
 import (
 	"errors"
@@ -755,7 +755,7 @@ func orderSameMapper(engine *xorm.Engine, t *testing.T) {
 
 func joinSameMapper(engine *xorm.Engine, t *testing.T) {
 	users := make([]Userinfo, 0)
-	err := engine.Join("LEFT", "`Userdetail`", "`Userinfo`.`(id)`=`Userdetail`.`(id)`").Find(&users)
+	err := engine.Join("LEFT", "`Userdetail`", "`Userinfo`.`(id)`=`Userdetail`.`Id`").Find(&users)
 	if err != nil {
 		t.Error(err)
 		panic(err)
@@ -1080,7 +1080,7 @@ func testCols(engine *xorm.Engine, t *testing.T) {
 
 func testColsSameMapper(engine *xorm.Engine, t *testing.T) {
 	users := []Userinfo{}
-	err := engine.Cols("(id), Username").Find(&users)
+	err := engine.Cols("id, Username").Find(&users)
 	if err != nil {
 		t.Error(err)
 		panic(err)
@@ -1089,7 +1089,8 @@ func testColsSameMapper(engine *xorm.Engine, t *testing.T) {
 	fmt.Println(users)
 
 	tmpUsers := []tempUser{}
-	err = engine.Table("Userinfo").Cols("(id), Username").Find(&tmpUsers)
+	// TODO: should use cache
+	err = engine.NoCache().Table("Userinfo").Cols("id, Username").Find(&tmpUsers)
 	if err != nil {
 		t.Error(err)
 		panic(err)
@@ -2062,7 +2063,8 @@ func testVersion(engine *xorm.Engine, t *testing.T) {
 
 func testDistinct(engine *xorm.Engine, t *testing.T) {
 	users := make([]Userinfo, 0)
-	err := engine.Distinct("departname").Find(&users)
+	departname := engine.TableMapper.Obj2Table("Departname")
+	err := engine.Distinct(departname).Find(&users)
 	if err != nil {
 		t.Error(err)
 		panic(err)
@@ -2079,7 +2081,7 @@ func testDistinct(engine *xorm.Engine, t *testing.T) {
 	}
 
 	users2 := make([]Depart, 0)
-	err = engine.Distinct("departname").Table(new(Userinfo)).Find(&users2)
+	err = engine.Distinct(departname).Table(new(Userinfo)).Find(&users2)
 	if err != nil {
 		t.Error(err)
 		panic(err)
@@ -2226,7 +2228,7 @@ func testPrefixTableName(engine *xorm.Engine, t *testing.T) {
 		panic(err)
 	}
 	tempEngine.ShowSQL = true
-	mapper := xorm.NewPrefixMapper(xorm.SnakeMapper{}, "xlw_")
+	mapper := core.NewPrefixMapper(core.SnakeMapper{}, "xlw_")
 	//tempEngine.SetMapper(mapper)
 	tempEngine.SetTableMapper(mapper)
 	exist, err := tempEngine.IsTableExist(&Userinfo{})
@@ -3738,7 +3740,7 @@ func testCompositeKey(engine *xorm.Engine, t *testing.T) {
 	}
 
 	var compositeKeyVal CompositeKey
-	has, err := engine.Id(xorm.PK{11, 22}).Get(&compositeKeyVal)
+	has, err := engine.Id(core.PK{11, 22}).Get(&compositeKeyVal)
 	if err != nil {
 		t.Error(err)
 	} else if !has {
@@ -3746,7 +3748,7 @@ func testCompositeKey(engine *xorm.Engine, t *testing.T) {
 	}
 
 	// test passing PK ptr, this test seem failed withCache
-	has, err = engine.Id(&xorm.PK{11, 22}).Get(&compositeKeyVal)
+	has, err = engine.Id(&core.PK{11, 22}).Get(&compositeKeyVal)
 	if err != nil {
 		t.Error(err)
 	} else if !has {
@@ -3754,14 +3756,14 @@ func testCompositeKey(engine *xorm.Engine, t *testing.T) {
 	}
 
 	compositeKeyVal = CompositeKey{UpdateStr: "test1"}
-	cnt, err = engine.Id(xorm.PK{11, 22}).Update(&compositeKeyVal)
+	cnt, err = engine.Id(core.PK{11, 22}).Update(&compositeKeyVal)
 	if err != nil {
 		t.Error(err)
 	} else if cnt != 1 {
 		t.Error(errors.New("can't update CompositeKey{11, 22}"))
 	}
 
-	cnt, err = engine.Id(xorm.PK{11, 22}).Delete(&CompositeKey{})
+	cnt, err = engine.Id(core.PK{11, 22}).Delete(&CompositeKey{})
 	if err != nil {
 		t.Error(err)
 	} else if cnt != 1 {
@@ -3803,7 +3805,7 @@ func testCompositeKey2(engine *xorm.Engine, t *testing.T) {
 	}
 
 	var user User
-	has, err := engine.Id(xorm.PK{"11", 22}).Get(&user)
+	has, err := engine.Id(core.PK{"11", 22}).Get(&user)
 	if err != nil {
 		t.Error(err)
 	} else if !has {
@@ -3811,7 +3813,7 @@ func testCompositeKey2(engine *xorm.Engine, t *testing.T) {
 	}
 
 	// test passing PK ptr, this test seem failed withCache
-	has, err = engine.Id(&xorm.PK{"11", 22}).Get(&user)
+	has, err = engine.Id(&core.PK{"11", 22}).Get(&user)
 	if err != nil {
 		t.Error(err)
 	} else if !has {
@@ -3819,14 +3821,14 @@ func testCompositeKey2(engine *xorm.Engine, t *testing.T) {
 	}
 
 	user = User{NickName: "test1"}
-	cnt, err = engine.Id(xorm.PK{"11", 22}).Update(&user)
+	cnt, err = engine.Id(core.PK{"11", 22}).Update(&user)
 	if err != nil {
 		t.Error(err)
 	} else if cnt != 1 {
 		t.Error(errors.New("can't update User{11, 22}"))
 	}
 
-	cnt, err = engine.Id(xorm.PK{"11", 22}).Delete(&User{})
+	cnt, err = engine.Id(core.PK{"11", 22}).Delete(&User{})
 	if err != nil {
 		t.Error(err)
 	} else if cnt != 1 {
@@ -3870,16 +3872,12 @@ func testAll(engine *xorm.Engine, t *testing.T) {
 }
 
 func testAll2(engine *xorm.Engine, t *testing.T) {
-	fmt.Println("-------------- combineTransaction --------------")
-	combineTransaction(engine, t)
 	fmt.Println("-------------- table --------------")
 	table(engine, t)
 	fmt.Println("-------------- createMultiTables --------------")
 	createMultiTables(engine, t)
 	fmt.Println("-------------- tableOp --------------")
 	tableOp(engine, t)
-	fmt.Println("-------------- testCols --------------")
-	testCols(engine, t)
 	fmt.Println("-------------- testCharst --------------")
 	testCharst(engine, t)
 	fmt.Println("-------------- testStoreEngine --------------")
@@ -3961,6 +3959,10 @@ func testAllSnakeMapper(engine *xorm.Engine, t *testing.T) {
 	join(engine, t)
 	fmt.Println("-------------- having --------------")
 	having(engine, t)
+	fmt.Println("-------------- combineTransaction --------------")
+	combineTransaction(engine, t)
+	fmt.Println("-------------- testCols --------------")
+	testCols(engine, t)
 }
 
 func testAllSameMapper(engine *xorm.Engine, t *testing.T) {
@@ -3976,4 +3978,8 @@ func testAllSameMapper(engine *xorm.Engine, t *testing.T) {
 	joinSameMapper(engine, t)
 	fmt.Println("-------------- having --------------")
 	havingSameMapper(engine, t)
+	fmt.Println("-------------- combineTransaction --------------")
+	combineTransactionSameMapper(engine, t)
+	fmt.Println("-------------- testCols --------------")
+	testColsSameMapper(engine, t)
 }
diff --git a/tests/benchmark_base_test.go b/tests/benchmark_base_test.go
index 5ea598e5..5570fa39 100644
--- a/tests/benchmark_base_test.go
+++ b/tests/benchmark_base_test.go
@@ -1,4 +1,4 @@
-package xorm
+package tests
 
 import (
 	"database/sql"
diff --git a/tests/mssql_test.go b/tests/mssql_test.go
index 101d07ae..e814d855 100644
--- a/tests/mssql_test.go
+++ b/tests/mssql_test.go
@@ -1,4 +1,4 @@
-package xorm
+package tests
 
 //
 // +build windows
@@ -9,6 +9,7 @@ import (
 
 	_ "github.com/lunny/godbc"
 	"github.com/lunny/xorm"
+	"github.com/lunny/xorm/caches"
 )
 
 const mssqlConnStr = "driver={SQL Server};Server=192.168.20.135;Database=xorm_test; uid=sa; pwd=1234;"
@@ -40,7 +41,7 @@ func TestMssqlWithCache(t *testing.T) {
 		t.Error(err)
 		return
 	}
-	engine.SetDefaultCacher(xorm.NewLRUCacher(xorm.NewMemoryStore(), 1000))
+	engine.SetDefaultCacher(xorm.NewLRUCacher(caches.NewMemoryStore(), 1000))
 	engine.ShowSQL = showTestSql
 	engine.ShowErr = showTestSql
 	engine.ShowWarn = showTestSql
@@ -113,7 +114,7 @@ func BenchmarkMssqlCacheInsert(t *testing.B) {
 		t.Error(err)
 		return
 	}
-	engine.SetDefaultCacher(xorm.NewLRUCacher(xorm.NewMemoryStore(), 1000))
+	engine.SetDefaultCacher(xorm.NewLRUCacher(caches.NewMemoryStore(), 1000))
 
 	doBenchInsert(engine, t)
 }
@@ -125,7 +126,7 @@ func BenchmarkMssqlCacheFind(t *testing.B) {
 		t.Error(err)
 		return
 	}
-	engine.SetDefaultCacher(xorm.NewLRUCacher(xorm.NewMemoryStore(), 1000))
+	engine.SetDefaultCacher(xorm.NewLRUCacher(caches.NewMemoryStore(), 1000))
 
 	doBenchFind(engine, t)
 }
@@ -137,7 +138,7 @@ func BenchmarkMssqlCacheFindPtr(t *testing.B) {
 		t.Error(err)
 		return
 	}
-	engine.SetDefaultCacher(xorm.NewLRUCacher(xorm.NewMemoryStore(), 1000))
+	engine.SetDefaultCacher(xorm.NewLRUCacher(caches.NewMemoryStore(), 1000))
 
 	doBenchFindPtr(engine, t)
 }
diff --git a/tests/mymysql_test.go b/tests/mymysql_test.go
index c64261dc..5646f95c 100644
--- a/tests/mymysql_test.go
+++ b/tests/mymysql_test.go
@@ -1,10 +1,11 @@
-package xorm
+package tests
 
 import (
 	"database/sql"
 	"testing"
 
 	"github.com/lunny/xorm"
+	"github.com/lunny/xorm/caches"
 	_ "github.com/ziutek/mymysql/godrv"
 )
 
@@ -49,7 +50,7 @@ func TestMyMysqlWithCache(t *testing.T) {
 		t.Error(err)
 		return
 	}
-	engine.SetDefaultCacher(xorm.NewLRUCacher(xorm.NewMemoryStore(), 1000))
+	engine.SetDefaultCacher(xorm.NewLRUCacher(caches.NewMemoryStore(), 1000))
 	engine.ShowSQL = showTestSql
 	engine.ShowErr = showTestSql
 	engine.ShowWarn = showTestSql
@@ -136,7 +137,7 @@ func BenchmarkMyMysqlCacheInsert(t *testing.B) {
 	}
 
 	defer engine.Close()
-	engine.SetDefaultCacher(xorm.NewLRUCacher(xorm.NewMemoryStore(), 1000))
+	engine.SetDefaultCacher(xorm.NewLRUCacher(caches.NewMemoryStore(), 1000))
 
 	doBenchInsert(engine, t)
 }
@@ -149,7 +150,7 @@ func BenchmarkMyMysqlCacheFind(t *testing.B) {
 	}
 
 	defer engine.Close()
-	engine.SetDefaultCacher(xorm.NewLRUCacher(xorm.NewMemoryStore(), 1000))
+	engine.SetDefaultCacher(xorm.NewLRUCacher(caches.NewMemoryStore(), 1000))
 
 	doBenchFind(engine, t)
 }
@@ -162,7 +163,7 @@ func BenchmarkMyMysqlCacheFindPtr(t *testing.B) {
 	}
 
 	defer engine.Close()
-	engine.SetDefaultCacher(xorm.NewLRUCacher(xorm.NewMemoryStore(), 1000))
+	engine.SetDefaultCacher(xorm.NewLRUCacher(caches.NewMemoryStore(), 1000))
 
 	doBenchFindPtr(engine, t)
 }
diff --git a/tests/mysql_test.go b/tests/mysql_test.go
index f42be512..38eebc55 100644
--- a/tests/mysql_test.go
+++ b/tests/mysql_test.go
@@ -1,4 +1,4 @@
-package xorm
+package tests
 
 import (
 	"database/sql"
@@ -6,6 +6,8 @@ import (
 
 	_ "github.com/go-sql-driver/mysql"
 	"github.com/lunny/xorm"
+	"github.com/lunny/xorm/caches"
+	"github.com/lunny/xorm/core"
 )
 
 /*
@@ -54,7 +56,7 @@ func TestMysqlSameMapper(t *testing.T) {
 	engine.ShowErr = showTestSql
 	engine.ShowWarn = showTestSql
 	engine.ShowDebug = showTestSql
-	engine.SetMapper(xorm.SameMapper{})
+	engine.SetMapper(core.SameMapper{})
 
 	testAll(engine, t)
 	testAllSameMapper(engine, t)
@@ -75,7 +77,7 @@ func TestMysqlWithCache(t *testing.T) {
 		t.Error(err)
 		return
 	}
-	engine.SetDefaultCacher(xorm.NewLRUCacher(xorm.NewMemoryStore(), 1000))
+	engine.SetDefaultCacher(xorm.NewLRUCacher(caches.NewMemoryStore(), 1000))
 	engine.ShowSQL = showTestSql
 	engine.ShowErr = showTestSql
 	engine.ShowWarn = showTestSql
@@ -99,8 +101,8 @@ func TestMysqlWithCacheSameMapper(t *testing.T) {
 		t.Error(err)
 		return
 	}
-	engine.SetMapper(xorm.SameMapper{})
-	engine.SetDefaultCacher(xorm.NewLRUCacher(xorm.NewMemoryStore(), 1000))
+	engine.SetMapper(core.SameMapper{})
+	engine.SetDefaultCacher(xorm.NewLRUCacher(caches.NewMemoryStore(), 1000))
 	engine.ShowSQL = showTestSql
 	engine.ShowErr = showTestSql
 	engine.ShowWarn = showTestSql
@@ -190,7 +192,7 @@ func BenchmarkMysqlCacheInsert(t *testing.B) {
 		t.Error(err)
 		return
 	}
-	engine.SetDefaultCacher(xorm.NewLRUCacher(xorm.NewMemoryStore(), 1000))
+	engine.SetDefaultCacher(xorm.NewLRUCacher(caches.NewMemoryStore(), 1000))
 
 	doBenchInsert(engine, t)
 }
@@ -202,7 +204,7 @@ func BenchmarkMysqlCacheFind(t *testing.B) {
 		t.Error(err)
 		return
 	}
-	engine.SetDefaultCacher(xorm.NewLRUCacher(xorm.NewMemoryStore(), 1000))
+	engine.SetDefaultCacher(xorm.NewLRUCacher(caches.NewMemoryStore(), 1000))
 
 	doBenchFind(engine, t)
 }
@@ -214,7 +216,7 @@ func BenchmarkMysqlCacheFindPtr(t *testing.B) {
 		t.Error(err)
 		return
 	}
-	engine.SetDefaultCacher(xorm.NewLRUCacher(xorm.NewMemoryStore(), 1000))
+	engine.SetDefaultCacher(xorm.NewLRUCacher(caches.NewMemoryStore(), 1000))
 
 	doBenchFindPtr(engine, t)
 }
diff --git a/tests/postgres_test.go b/tests/postgres_test.go
index 9c2ee2d8..85e926cc 100644
--- a/tests/postgres_test.go
+++ b/tests/postgres_test.go
@@ -1,4 +1,4 @@
-package xorm
+package tests
 
 import (
 	"database/sql"
@@ -6,6 +6,8 @@ import (
 
 	_ "github.com/lib/pq"
 	"github.com/lunny/xorm"
+	"github.com/lunny/xorm/caches"
+	"github.com/lunny/xorm/core"
 )
 
 //var connStr string = "dbname=xorm_test user=lunny password=1234 sslmode=disable"
@@ -59,7 +61,7 @@ func TestPostgresWithCache(t *testing.T) {
 		t.Error(err)
 		return
 	}
-	engine.SetDefaultCacher(xorm.NewLRUCacher(xorm.NewMemoryStore(), 1000))
+	engine.SetDefaultCacher(xorm.NewLRUCacher(caches.NewMemoryStore(), 1000))
 	defer engine.Close()
 	engine.ShowSQL = showTestSql
 	engine.ShowErr = showTestSql
@@ -78,7 +80,7 @@ func TestPostgresSameMapper(t *testing.T) {
 		return
 	}
 	defer engine.Close()
-	engine.SetMapper(xorm.SameMapper{})
+	engine.SetMapper(core.SameMapper{})
 	engine.ShowSQL = showTestSql
 	engine.ShowErr = showTestSql
 	engine.ShowWarn = showTestSql
@@ -96,9 +98,9 @@ func TestPostgresWithCacheSameMapper(t *testing.T) {
 		t.Error(err)
 		return
 	}
-	engine.SetDefaultCacher(xorm.NewLRUCacher(xorm.NewMemoryStore(), 1000))
+	engine.SetDefaultCacher(xorm.NewLRUCacher(caches.NewMemoryStore(), 1000))
 	defer engine.Close()
-	engine.SetMapper(xorm.SameMapper{})
+	engine.SetMapper(core.SameMapper{})
 	engine.ShowSQL = showTestSql
 	engine.ShowErr = showTestSql
 	engine.ShowWarn = showTestSql
@@ -168,7 +170,7 @@ func BenchmarkPostgresCacheInsert(t *testing.B) {
 		t.Error(err)
 		return
 	}
-	engine.SetDefaultCacher(xorm.NewLRUCacher(xorm.NewMemoryStore(), 1000))
+	engine.SetDefaultCacher(xorm.NewLRUCacher(caches.NewMemoryStore(), 1000))
 
 	doBenchInsert(engine, t)
 }
@@ -181,7 +183,7 @@ func BenchmarkPostgresCacheFind(t *testing.B) {
 		t.Error(err)
 		return
 	}
-	engine.SetDefaultCacher(xorm.NewLRUCacher(xorm.NewMemoryStore(), 1000))
+	engine.SetDefaultCacher(xorm.NewLRUCacher(caches.NewMemoryStore(), 1000))
 
 	doBenchFind(engine, t)
 }
@@ -194,7 +196,7 @@ func BenchmarkPostgresCacheFindPtr(t *testing.B) {
 		t.Error(err)
 		return
 	}
-	engine.SetDefaultCacher(xorm.NewLRUCacher(xorm.NewMemoryStore(), 1000))
+	engine.SetDefaultCacher(xorm.NewLRUCacher(caches.NewMemoryStore(), 1000))
 
 	doBenchFindPtr(engine, t)
 }
diff --git a/tests/sqlite3_test.go b/tests/sqlite3_test.go
index aa10af64..1f982e29 100644
--- a/tests/sqlite3_test.go
+++ b/tests/sqlite3_test.go
@@ -1,4 +1,4 @@
-package xorm
+package tests
 
 import (
 	"database/sql"
@@ -6,6 +6,8 @@ import (
 	"testing"
 
 	"github.com/lunny/xorm"
+	"github.com/lunny/xorm/caches"
+	"github.com/lunny/xorm/core"
 	_ "github.com/mattn/go-sqlite3"
 )
 
@@ -44,7 +46,7 @@ func TestSqlite3WithCache(t *testing.T) {
 		t.Error(err)
 		return
 	}
-	engine.SetDefaultCacher(xorm.NewLRUCacher(xorm.NewMemoryStore(), 1000))
+	engine.SetDefaultCacher(xorm.NewLRUCacher(caches.NewMemoryStore(), 1000))
 	engine.ShowSQL = showTestSql
 	engine.ShowErr = showTestSql
 	engine.ShowWarn = showTestSql
@@ -62,7 +64,7 @@ func TestSqlite3SameMapper(t *testing.T) {
 		t.Error(err)
 		return
 	}
-	engine.SetMapper(xorm.SameMapper{})
+	engine.SetMapper(core.SameMapper{})
 	engine.ShowSQL = showTestSql
 	engine.ShowErr = showTestSql
 	engine.ShowWarn = showTestSql
@@ -81,8 +83,8 @@ func TestSqlite3WithCacheSameMapper(t *testing.T) {
 		t.Error(err)
 		return
 	}
-	engine.SetMapper(xorm.SameMapper{})
-	engine.SetDefaultCacher(xorm.NewLRUCacher(xorm.NewMemoryStore(), 1000))
+	engine.SetMapper(core.SameMapper{})
+	engine.SetDefaultCacher(xorm.NewLRUCacher(caches.NewMemoryStore(), 1000))
 	engine.ShowSQL = showTestSql
 	engine.ShowErr = showTestSql
 	engine.ShowWarn = showTestSql
@@ -152,7 +154,7 @@ func BenchmarkSqlite3CacheInsert(t *testing.B) {
 		t.Error(err)
 		return
 	}
-	engine.SetDefaultCacher(xorm.NewLRUCacher(xorm.NewMemoryStore(), 1000))
+	engine.SetDefaultCacher(xorm.NewLRUCacher(caches.NewMemoryStore(), 1000))
 	doBenchInsert(engine, t)
 }
 
@@ -164,7 +166,7 @@ func BenchmarkSqlite3CacheFind(t *testing.B) {
 		t.Error(err)
 		return
 	}
-	engine.SetDefaultCacher(xorm.NewLRUCacher(xorm.NewMemoryStore(), 1000))
+	engine.SetDefaultCacher(xorm.NewLRUCacher(caches.NewMemoryStore(), 1000))
 	doBenchFind(engine, t)
 }
 
@@ -176,6 +178,6 @@ func BenchmarkSqlite3CacheFindPtr(t *testing.B) {
 		t.Error(err)
 		return
 	}
-	engine.SetDefaultCacher(xorm.NewLRUCacher(xorm.NewMemoryStore(), 1000))
+	engine.SetDefaultCacher(xorm.NewLRUCacher(caches.NewMemoryStore(), 1000))
 	doBenchFindPtr(engine, t)
 }
diff --git a/tests/testdata/mysql_ddl.sql b/tests/testdata/mysql_ddl.sql
index db20aa33..b1fcca5b 100644
--- a/tests/testdata/mysql_ddl.sql
+++ b/tests/testdata/mysql_ddl.sql
@@ -1,5 +1,8 @@
---DROP DATABASE xorm_test;
---DROP DATABASE xorm_test2;
+DROP DATABASE xorm_test;
+DROP DATABASE xorm_test1;
+DROP DATABASE xorm_test2;
+DROP DATABASE xorm_test3;
 CREATE DATABASE IF NOT EXISTS xorm_test CHARACTER SET utf8 COLLATE utf8_general_ci;
+CREATE DATABASE IF NOT EXISTS xorm_test1 CHARACTER SET utf8 COLLATE utf8_general_ci;
 CREATE DATABASE IF NOT EXISTS xorm_test2 CHARACTER SET utf8 COLLATE utf8_general_ci;
 CREATE DATABASE IF NOT EXISTS xorm_test3 CHARACTER SET utf8 COLLATE utf8_general_ci;
diff --git a/xorm.go b/xorm.go
index 5826db60..7ea51473 100644
--- a/xorm.go
+++ b/xorm.go
@@ -7,7 +7,9 @@ import (
 	"reflect"
 	"runtime"
 	"sync"
+	"time"
 
+	"github.com/lunny/xorm/caches"
 	"github.com/lunny/xorm/core"
 	_ "github.com/lunny/xorm/dialects"
 	_ "github.com/lunny/xorm/drivers"
@@ -46,9 +48,9 @@ func NewEngine(driverName string, dataSourceName string) (*Engine, error) {
 
 	engine := &Engine{DriverName: driverName,
 		DataSourceName: dataSourceName, dialect: dialect,
-		tableCachers: make(map[reflect.Type]Cacher)}
+		tableCachers: make(map[reflect.Type]core.Cacher)}
 
-	engine.SetMapper(SnakeMapper{})
+	engine.SetMapper(core.SnakeMapper{})
 
 	engine.Filters = dialect.Filters()
 
@@ -65,3 +67,11 @@ func NewEngine(driverName string, dataSourceName string) (*Engine, error) {
 	runtime.SetFinalizer(engine, close)
 	return engine, err
 }
+
+func NewLRUCacher(store core.CacheStore, max int) *caches.LRUCacher {
+	return caches.NewLRUCacher(store, core.CacheExpired, core.CacheMaxMemory, max)
+}
+
+func NewLRUCacher2(store core.CacheStore, expired time.Duration, max int) *caches.LRUCacher {
+	return caches.NewLRUCacher(store, expired, 0, max)
+}