diff --git a/cache.go b/cache.go
index bedd22a7..b9bf6e0d 100644
--- a/cache.go
+++ b/cache.go
@@ -20,7 +20,7 @@ const (
 
 // CacheStore is a interface to store cache
 type CacheStore interface {
-	// key is primary key or composite primary key or unique key's value
+	// key is primary key or composite primary key
 	// value is struct's pointer
 	// key format : <tablename>-p-<pk1>-<pk2>...
 	Put(key string, value interface{}) error
diff --git a/db.go b/db.go
index ed97987a..1f70a926 100644
--- a/db.go
+++ b/db.go
@@ -8,11 +8,6 @@ import (
 	"sync"
 )
 
-var (
-	ErrNoMapPointer    = errors.New("mp should be a map's pointer")
-	ErrNoStructPointer = errors.New("mp should be a map's pointer")
-)
-
 func MapToSlice(query string, mp interface{}) (string, []interface{}, error) {
 	vv := reflect.ValueOf(mp)
 	if vv.Kind() != reflect.Ptr || vv.Elem().Kind() != reflect.Map {
@@ -252,7 +247,7 @@ type Rows struct {
 }
 
 // scan data to a struct's pointer according field index
-func (rs *Rows) ScanStruct(dest ...interface{}) error {
+func (rs *Rows) ScanStructByIndex(dest ...interface{}) error {
 	if len(dest) == 0 {
 		return errors.New("at least one struct")
 	}
@@ -319,7 +314,7 @@ func fieldByName(v reflect.Value, name string) reflect.Value {
 }
 
 // scan data to a struct's pointer according field name
-func (rs *Rows) ScanStruct2(dest interface{}) error {
+func (rs *Rows) ScanStructByName(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")
diff --git a/dialect.go b/dialect.go
index 08a4a4c5..f419cdb6 100644
--- a/dialect.go
+++ b/dialect.go
@@ -30,6 +30,9 @@ type Dialect interface {
 	DBType() DbType
 	SqlType(*Column) string
 
+	DriverName() string
+	DataSourceName() string
+
 	QuoteStr() string
 	AndStr() string
 	OrStr() string
@@ -43,21 +46,28 @@ type Dialect interface {
 	IndexOnTable() bool
 	ShowCreateNull() bool
 
-	DropTableSql(tableName string) string
 	IndexCheckSql(tableName, idxName string) (string, []interface{})
 	TableCheckSql(tableName string) (string, []interface{})
-	ColumnCheckSql(tableName, colName string, isPK bool) (string, []interface{})
+	//ColumnCheckSql(tableName, colName string) (string, []interface{})
+
+	//IsTableExist(tableName string) (bool, error)
+	//IsIndexExist(tableName string, idx *Index) (bool, error)
+	IsColumnExist(tableName string, col *Column) (bool, error)
+
 	CreateTableSql(table *Table, tableName, storeEngine, charset string) string
+	DropTableSql(tableName string) string
 	CreateIndexSql(tableName string, index *Index) string
 
 	GetColumns(tableName string) ([]string, map[string]*Column, error)
 	GetTables() ([]*Table, error)
 	GetIndexes(tableName string) (map[string]*Index, error)
 
-	Filters() []Filter
+	// Get data from db cell to a struct's field
+	//GetData(col *Column, fieldValue *reflect.Value, cellData interface{}) error
+	// Set field data to db
+	//SetData(col *Column, fieldValue *refelct.Value) (interface{}, error)
 
-	DriverName() string
-	DataSourceName() string
+	Filters() []Filter
 }
 
 func OpenDialect(dialect Dialect) (*DB, error) {
@@ -126,6 +136,22 @@ func (db *Base) DropTableSql(tableName string) string {
 	return fmt.Sprintf("DROP TABLE IF EXISTS `%s`", tableName)
 }
 
+func (db *Base) IsColumnExist(tableName string, col *Column) (bool, error) {
+	args := []interface{}{db.DbName, tableName, col.Name}
+	query := "SELECT `COLUMN_NAME` FROM `INFORMATION_SCHEMA`.`COLUMNS` WHERE `TABLE_SCHEMA` = ? AND `TABLE_NAME` = ? AND `COLUMN_NAME` = ?"
+
+	rows, err := db.DB().Query(query, args...)
+	if err != nil {
+		return false, err
+	}
+	defer rows.Close()
+
+	if rows.Next() {
+		return true, nil
+	}
+	return false, ErrNotExist
+}
+
 func (db *Base) CreateIndexSql(tableName string, index *Index) string {
 	quote := db.Quote
 	var unique string
diff --git a/error.go b/error.go
new file mode 100644
index 00000000..b79f188e
--- /dev/null
+++ b/error.go
@@ -0,0 +1,10 @@
+package core
+
+import "errors"
+
+var (
+	ErrNoMapPointer    = errors.New("mp should be a map's pointer")
+	ErrNoStructPointer = errors.New("mp should be a map's pointer")
+	ErrNotExist        = errors.New("Not exist")
+	ErrIgnore          = errors.New("Ignore")
+)
diff --git a/table.go b/table.go
index aadcc9a8..9ccae74e 100644
--- a/table.go
+++ b/table.go
@@ -18,6 +18,8 @@ type Table struct {
 	Updated       string
 	Version       string
 	Cacher        Cacher
+	storeEngine   string
+	charset       string
 }
 
 func (table *Table) Columns() map[string]*Column {