diff --git a/dialects/dialect.go b/dialects/dialect.go
index 7d816bda..c591cc7b 100644
--- a/dialects/dialect.go
+++ b/dialects/dialect.go
@@ -31,7 +31,7 @@ type URI struct {
 
 // Dialect represents a kind of database
 type Dialect interface {
-	Init(*core.DB, *URI /*, string, string*/) error
+	Init(*core.DB, *URI) error
 	URI() *URI
 	DB() *core.DB
 	DBType() schemas.DBType
diff --git a/dialects/mssql.go b/dialects/mssql.go
index 3c95dd20..558abdfc 100644
--- a/dialects/mssql.go
+++ b/dialects/mssql.go
@@ -210,8 +210,8 @@ type mssql struct {
 	Base
 }
 
-func (db *mssql) Init(d *core.DB, uri *URI /*, drivername, dataSourceName string*/) error {
-	return db.Base.Init(d, db, uri /*, drivername, dataSourceName*/)
+func (db *mssql) Init(d *core.DB, uri *URI) error {
+	return db.Base.Init(d, db, uri)
 }
 
 func (db *mssql) SQLType(c *schemas.Column) string {
diff --git a/dialects/mysql.go b/dialects/mysql.go
index 7c41ecf6..939a7cf1 100644
--- a/dialects/mysql.go
+++ b/dialects/mysql.go
@@ -177,8 +177,8 @@ type mysql struct {
 	rowFormat         string
 }
 
-func (db *mysql) Init(d *core.DB, uri *URI /*, drivername, dataSourceName string*/) error {
-	return db.Base.Init(d, db, uri /*, drivername, dataSourceName*/)
+func (db *mysql) Init(d *core.DB, uri *URI) error {
+	return db.Base.Init(d, db, uri)
 }
 
 func (db *mysql) SetParams(params map[string]string) {
diff --git a/dialects/oracle.go b/dialects/oracle.go
index 49c65837..4a8162ac 100644
--- a/dialects/oracle.go
+++ b/dialects/oracle.go
@@ -504,8 +504,8 @@ type oracle struct {
 	Base
 }
 
-func (db *oracle) Init(d *core.DB, uri *URI /*, drivername, dataSourceName string*/) error {
-	return db.Base.Init(d, db, uri /*, drivername, dataSourceName*/)
+func (db *oracle) Init(d *core.DB, uri *URI) error {
+	return db.Base.Init(d, db, uri)
 }
 
 func (db *oracle) SQLType(c *schemas.Column) string {
diff --git a/dialects/postgres.go b/dialects/postgres.go
index ad3c8c68..f92202cd 100644
--- a/dialects/postgres.go
+++ b/dialects/postgres.go
@@ -774,8 +774,8 @@ type postgres struct {
 	Base
 }
 
-func (db *postgres) Init(d *core.DB, uri *URI /*, drivername, dataSourceName string*/) error {
-	err := db.Base.Init(d, db, uri /*, drivername, dataSourceName*/)
+func (db *postgres) Init(d *core.DB, uri *URI) error {
+	err := db.Base.Init(d, db, uri)
 	if err != nil {
 		return err
 	}
diff --git a/dialects/sqlite3.go b/dialects/sqlite3.go
index 3b9cb97c..39138b13 100644
--- a/dialects/sqlite3.go
+++ b/dialects/sqlite3.go
@@ -149,8 +149,8 @@ type sqlite3 struct {
 	Base
 }
 
-func (db *sqlite3) Init(d *core.DB, uri *URI /*, drivername, dataSourceName string*/) error {
-	return db.Base.Init(d, db, uri /*, drivername, dataSourceName*/)
+func (db *sqlite3) Init(d *core.DB, uri *URI) error {
+	return db.Base.Init(d, db, uri)
 }
 
 func (db *sqlite3) SQLType(c *schemas.Column) string {
diff --git a/engine.go b/engine.go
index 31d891dc..cc8a74a0 100644
--- a/engine.go
+++ b/engine.go
@@ -64,7 +64,7 @@ func (engine *Engine) BufferSize(size int) *Session {
 // ShowSQL show SQL statement or not on logger if log level is great than INFO
 func (engine *Engine) ShowSQL(show ...bool) {
 	engine.logger.ShowSQL(show...)
-	engine.db.Logger = engine.logger
+	engine.DB().Logger = engine.logger
 }
 
 // Logger return the logger interface
@@ -82,7 +82,7 @@ func (engine *Engine) SetLogger(logger interface{}) {
 		realLogger = t
 	}
 	engine.logger = realLogger
-	engine.db.Logger = realLogger
+	engine.DB().Logger = realLogger
 }
 
 // SetLogLevel sets the logger level
@@ -167,17 +167,17 @@ func (engine *Engine) AutoIncrStr() string {
 
 // SetConnMaxLifetime sets the maximum amount of time a connection may be reused.
 func (engine *Engine) SetConnMaxLifetime(d time.Duration) {
-	engine.db.SetConnMaxLifetime(d)
+	engine.DB().SetConnMaxLifetime(d)
 }
 
 // SetMaxOpenConns is only available for go 1.2+
 func (engine *Engine) SetMaxOpenConns(conns int) {
-	engine.db.SetMaxOpenConns(conns)
+	engine.DB().SetMaxOpenConns(conns)
 }
 
 // SetMaxIdleConns set the max idle connections on pool, default is 2
 func (engine *Engine) SetMaxIdleConns(conns int) {
-	engine.db.SetMaxIdleConns(conns)
+	engine.DB().SetMaxIdleConns(conns)
 }
 
 // SetDefaultCacher set the default cacher. Xorm's default not enable cacher.
@@ -218,7 +218,7 @@ func (engine *Engine) NewDB() (*core.DB, error) {
 
 // DB return the wrapper of sql.DB
 func (engine *Engine) DB() *core.DB {
-	return engine.db
+	return engine.dialect.DB()
 }
 
 // Dialect return database dialect
@@ -235,7 +235,7 @@ func (engine *Engine) NewSession() *Session {
 
 // Close the engine
 func (engine *Engine) Close() error {
-	return engine.db.Close()
+	return engine.DB().Close()
 }
 
 // Ping tests if database is alive
diff --git a/session.go b/session.go
index db990684..07b99594 100644
--- a/session.go
+++ b/session.go
@@ -284,7 +284,7 @@ func (session *Session) Having(conditions string) *Session {
 // DB db return the wrapper of sql.DB
 func (session *Session) DB() *core.DB {
 	if session.db == nil {
-		session.db = session.engine.db
+		session.db = session.engine.DB()
 		session.stmtCache = make(map[uint32]*core.Stmt, 0)
 	}
 	return session.db
diff --git a/session_tx.go b/session_tx.go
index 489489f3..cd23cf89 100644
--- a/session_tx.go
+++ b/session_tx.go
@@ -34,7 +34,7 @@ func (session *Session) Rollback() error {
 		session.isAutoCommit = true
 
 		start := time.Now()
-		needSQL := session.engine.db.NeedLogSQL(session.ctx)
+		needSQL := session.DB().NeedLogSQL(session.ctx)
 		if needSQL {
 			session.engine.logger.BeforeSQL(log.LogContext{
 				Ctx: session.ctx,
@@ -63,7 +63,7 @@ func (session *Session) Commit() error {
 		session.isAutoCommit = true
 
 		start := time.Now()
-		needSQL := session.engine.db.NeedLogSQL(session.ctx)
+		needSQL := session.DB().NeedLogSQL(session.ctx)
 		if needSQL {
 			session.engine.logger.BeforeSQL(log.LogContext{
 				Ctx: session.ctx,
diff --git a/xorm.go b/xorm.go
index 51915940..3618b718 100644
--- a/xorm.go
+++ b/xorm.go
@@ -8,13 +8,11 @@ package xorm
 
 import (
 	"context"
-	"fmt"
 	"os"
 	"runtime"
 	"time"
 
 	"xorm.io/xorm/caches"
-	"xorm.io/xorm/core"
 	"xorm.io/xorm/dialects"
 	"xorm.io/xorm/log"
 	"xorm.io/xorm/names"
@@ -34,27 +32,7 @@ func close(engine *Engine) {
 // NewEngine new a db manager according to the parameter. Currently support four
 // drivers
 func NewEngine(driverName string, dataSourceName string) (*Engine, error) {
-	driver := dialects.QueryDriver(driverName)
-	if driver == nil {
-		return nil, fmt.Errorf("Unsupported driver name: %v", driverName)
-	}
-
-	uri, err := driver.Parse(driverName, dataSourceName)
-	if err != nil {
-		return nil, err
-	}
-
-	dialect := dialects.QueryDialect(uri.DBType)
-	if dialect == nil {
-		return nil, fmt.Errorf("Unsupported dialect type: %v", uri.DBType)
-	}
-
-	db, err := core.Open(driverName, dataSourceName)
-	if err != nil {
-		return nil, err
-	}
-
-	err = dialect.Init(db, uri /*, driverName, dataSourceName*/)
+	dialect, err := dialects.OpenDialect(driverName, dataSourceName)
 	if err != nil {
 		return nil, err
 	}
@@ -64,7 +42,6 @@ func NewEngine(driverName string, dataSourceName string) (*Engine, error) {
 	tagParser := tags.NewParser("xorm", dialect, mapper, mapper, cacherMgr)
 
 	engine := &Engine{
-		db:             db,
 		dialect:        dialect,
 		TZLocation:     time.Local,
 		defaultContext: context.Background(),
@@ -74,7 +51,7 @@ func NewEngine(driverName string, dataSourceName string) (*Engine, error) {
 		dataSourceName: dataSourceName,
 	}
 
-	if uri.DBType == schemas.SQLITE {
+	if dialect.URI().DBType == schemas.SQLITE {
 		engine.DatabaseTZ = time.UTC
 	} else {
 		engine.DatabaseTZ = time.Local