diff --git a/dialects/mysql/mysql.go b/dialects/mysql/mysql.go
index 3b456891..5fcc2d69 100644
--- a/dialects/mysql/mysql.go
+++ b/dialects/mysql/mysql.go
@@ -23,9 +23,8 @@ func Open(dsn string) gorm.Dialector {
 func (dialector Dialector) Initialize(db *gorm.DB) (err error) {
 	// register callbacks
 	callbacks.RegisterDefaultCallbacks(db)
-	db.DB, err = sql.Open("sqlite3", dialector.DSN)
-
-	return nil
+	db.DB, err = sql.Open("mysql", dialector.DSN)
+	return
 }
 
 func (dialector Dialector) Migrator(db *gorm.DB) gorm.Migrator {
@@ -75,9 +74,13 @@ func (dialector Dialector) DataTypeOf(field *schema.Field) string {
 		return "double"
 	case schema.String:
 		size := field.Size
+		if field.PrimaryKey {
+			size = 256
+		}
+
 		if size >= 65536 && size <= int(math.Pow(2, 24)) {
 			return "mediumtext"
-		} else if size > int(math.Pow(2, 24)) || size < 0 {
+		} else if size > int(math.Pow(2, 24)) || size <= 0 {
 			return "longtext"
 		}
 		return fmt.Sprintf("varchar(%d)", size)
diff --git a/dialects/mysql/mysql_test.go b/dialects/mysql/mysql_test.go
index 49c26915..7fd5e373 100644
--- a/dialects/mysql/mysql_test.go
+++ b/dialects/mysql/mysql_test.go
@@ -1,12 +1,33 @@
 package mysql_test
 
 import (
+	"fmt"
 	"testing"
 
 	"github.com/jinzhu/gorm"
 	"github.com/jinzhu/gorm/dialects/mysql"
+	"github.com/jinzhu/gorm/tests"
 )
 
 func TestOpen(t *testing.T) {
 	gorm.Open(mysql.Open("gorm:gorm@tcp(localhost:9910)/gorm?charset=utf8&parseTime=True"), nil)
 }
+
+var (
+	DB  *gorm.DB
+	err error
+)
+
+func init() {
+	if DB, err = gorm.Open(mysql.Open("gorm:gorm@tcp(localhost:9910)/gorm?charset=utf8&parseTime=True"), &gorm.Config{}); err != nil {
+		panic(fmt.Sprintf("failed to initialize database, got error %v", err))
+	}
+}
+
+func TestCURD(t *testing.T) {
+	tests.RunTestsSuit(t, DB)
+}
+
+func TestMigrate(t *testing.T) {
+	tests.TestMigrate(t, DB)
+}
diff --git a/dialects/sqlite/sqlite.go b/dialects/sqlite/sqlite.go
index 38cd760b..54fa7de0 100644
--- a/dialects/sqlite/sqlite.go
+++ b/dialects/sqlite/sqlite.go
@@ -21,7 +21,6 @@ func Open(dsn string) gorm.Dialector {
 func (dialector Dialector) Initialize(db *gorm.DB) (err error) {
 	// register callbacks
 	callbacks.RegisterDefaultCallbacks(db)
-
 	db.DB, err = sql.Open("sqlite3", dialector.DSN)
 	return
 }
diff --git a/finisher_api.go b/finisher_api.go
index c9b58861..2c5d4f65 100644
--- a/finisher_api.go
+++ b/finisher_api.go
@@ -140,7 +140,7 @@ func (db *DB) Transaction(fc func(tx *DB) error, opts ...*sql.TxOptions) (err er
 		}
 	}()
 
-	err = fc(tx)
+	err = fc(tx.Session(&Session{}))
 
 	if err == nil {
 		err = tx.Commit().Error
diff --git a/migrator/migrator.go b/migrator/migrator.go
index e3097abd..a5ec1a62 100644
--- a/migrator/migrator.go
+++ b/migrator/migrator.go
@@ -18,8 +18,9 @@ type Migrator struct {
 
 // Config schema config
 type Config struct {
-	CreateIndexAfterCreateTable bool
-	DB                          *gorm.DB
+	CreateIndexAfterCreateTable             bool
+	AllowDeferredConstraintsWhenAutoMigrate bool
+	DB                                      *gorm.DB
 	gorm.Dialector
 }
 
@@ -47,17 +48,17 @@ func (m Migrator) DataTypeOf(field *schema.Field) string {
 // AutoMigrate
 func (m Migrator) AutoMigrate(values ...interface{}) error {
 	// TODO smart migrate data type
-
 	for _, value := range values {
-		if !m.DB.Migrator().HasTable(value) {
-			if err := m.DB.Migrator().CreateTable(value); err != nil {
+		tx := m.DB.Session(&gorm.Session{})
+		if !tx.Migrator().HasTable(value) {
+			if err := tx.Migrator().CreateTable(value); err != nil {
 				return err
 			}
 		} else {
 			if err := m.RunWithValue(value, func(stmt *gorm.Statement) error {
 				for _, field := range stmt.Schema.FieldsByDBName {
-					if !m.DB.Migrator().HasColumn(value, field.DBName) {
-						if err := m.DB.Migrator().AddColumn(value, field.DBName); err != nil {
+					if !tx.Migrator().HasColumn(value, field.DBName) {
+						if err := tx.Migrator().AddColumn(value, field.DBName); err != nil {
 							return err
 						}
 					}
@@ -65,16 +66,16 @@ func (m Migrator) AutoMigrate(values ...interface{}) error {
 
 				for _, rel := range stmt.Schema.Relationships.Relations {
 					if constraint := rel.ParseConstraint(); constraint != nil {
-						if !m.DB.Migrator().HasConstraint(value, constraint.Name) {
-							if err := m.DB.Migrator().CreateConstraint(value, constraint.Name); err != nil {
+						if !tx.Migrator().HasConstraint(value, constraint.Name) {
+							if err := tx.Migrator().CreateConstraint(value, constraint.Name); err != nil {
 								return err
 							}
 						}
 					}
 
 					for _, chk := range stmt.Schema.ParseCheckConstraints() {
-						if !m.DB.Migrator().HasConstraint(value, chk.Name) {
-							if err := m.DB.Migrator().CreateConstraint(value, chk.Name); err != nil {
+						if !tx.Migrator().HasConstraint(value, chk.Name) {
+							if err := tx.Migrator().CreateConstraint(value, chk.Name); err != nil {
 								return err
 							}
 						}
@@ -83,8 +84,8 @@ func (m Migrator) AutoMigrate(values ...interface{}) error {
 					// create join table
 					if rel.JoinTable != nil {
 						joinValue := reflect.New(rel.JoinTable.ModelType).Interface()
-						if !m.DB.Migrator().HasTable(joinValue) {
-							defer m.DB.Migrator().CreateTable(joinValue)
+						if !tx.Migrator().HasTable(joinValue) {
+							defer tx.Migrator().CreateTable(joinValue)
 						}
 					}
 				}
@@ -100,6 +101,7 @@ func (m Migrator) AutoMigrate(values ...interface{}) error {
 
 func (m Migrator) CreateTable(values ...interface{}) error {
 	for _, value := range values {
+		tx := m.DB.Session(&gorm.Session{})
 		if err := m.RunWithValue(value, func(stmt *gorm.Statement) error {
 			var (
 				createTableSQL          = "CREATE TABLE ? ("
@@ -144,10 +146,10 @@ func (m Migrator) CreateTable(values ...interface{}) error {
 
 			for _, idx := range stmt.Schema.ParseIndexes() {
 				if m.CreateIndexAfterCreateTable {
-					m.DB.Migrator().CreateIndex(value, idx.Name)
+					tx.Migrator().CreateIndex(value, idx.Name)
 				} else {
 					createTableSQL += "INDEX ? ?,"
-					values = append(values, clause.Expr{SQL: idx.Name}, m.DB.Migrator().(BuildIndexOptionsInterface).BuildIndexOptions(idx.Fields, stmt))
+					values = append(values, clause.Expr{SQL: idx.Name}, tx.Migrator().(BuildIndexOptionsInterface).BuildIndexOptions(idx.Fields, stmt))
 				}
 			}
 
@@ -161,8 +163,8 @@ func (m Migrator) CreateTable(values ...interface{}) error {
 				// create join table
 				if rel.JoinTable != nil {
 					joinValue := reflect.New(rel.JoinTable.ModelType).Interface()
-					if !m.DB.Migrator().HasTable(joinValue) {
-						defer m.DB.Migrator().CreateTable(joinValue)
+					if !tx.Migrator().HasTable(joinValue) {
+						defer tx.Migrator().CreateTable(joinValue)
 					}
 				}
 			}
@@ -175,7 +177,7 @@ func (m Migrator) CreateTable(values ...interface{}) error {
 			createTableSQL = strings.TrimSuffix(createTableSQL, ",")
 
 			createTableSQL += ")"
-			return m.DB.Exec(createTableSQL, values...).Error
+			return tx.Exec(createTableSQL, values...).Error
 		}); err != nil {
 			return err
 		}
@@ -185,8 +187,9 @@ func (m Migrator) CreateTable(values ...interface{}) error {
 
 func (m Migrator) DropTable(values ...interface{}) error {
 	for _, value := range values {
+		tx := m.DB.Session(&gorm.Session{})
 		if err := m.RunWithValue(value, func(stmt *gorm.Statement) error {
-			return m.DB.Exec("DROP TABLE ?", clause.Table{Name: stmt.Table}).Error
+			return tx.Exec("DROP TABLE ?", clause.Table{Name: stmt.Table}).Error
 		}); err != nil {
 			return err
 		}
diff --git a/tests/migrate.go b/tests/migrate.go
index 9f7e2d67..477f0ad6 100644
--- a/tests/migrate.go
+++ b/tests/migrate.go
@@ -7,7 +7,7 @@ import (
 )
 
 func TestMigrate(t *testing.T, db *gorm.DB) {
-	allModels := []interface{}{&User{}, &Account{}, &Pet{}, &Toy{}, &Company{}, &Language{}}
+	allModels := []interface{}{&User{}, &Account{}, &Pet{}, &Company{}, &Toy{}, &Language{}}
 
 	for _, m := range allModels {
 		if db.Migrator().HasTable(m) {
diff --git a/tests/model.go b/tests/model.go
index ac2156c7..b2d5efe1 100644
--- a/tests/model.go
+++ b/tests/model.go
@@ -21,7 +21,7 @@ type User struct {
 	Toys      []Toy `gorm:"polymorphic:Owner"`
 	CompanyID *int
 	Company   Company
-	ManagerID int
+	ManagerID uint
 	Manager   *User
 	Team      []User     `gorm:"foreignkey:ManagerID"`
 	Languages []Language `gorm:"many2many:UserSpeak"`
@@ -49,7 +49,7 @@ type Toy struct {
 }
 
 type Company struct {
-	ID   uint
+	ID   int
 	Name string
 }