}
	wg.Wait()

	conn, ok := tx.ConnPool.(*gorm.PreparedStmtDB)
	AssertEqual(t, ok, true)
	AssertEqual(t, len(conn.Stmts), 2)
	for _, stmt := range conn.Stmts {
		if stmt == nil {
			t.Fatalf("stmt cannot bee nil")
		}
	}

	AssertEqual(t, sqlDB.Stats().InUse, 0)
}

func TestPreparedStmtInTransaction(t *testing.T) {
	user := User{Name: "jinzhu"}

	if err := DB.Transaction(func(tx *gorm.DB) error {

					subName := field.Name
					const key = "COMPOSITE"
					if composite, found := settings[key]; found {
						if len(composite) == 0 || composite == key {
							err = fmt.Errorf(
								"The composite tag of %s.%s cannot be empty",
								field.Schema.Name,
								field.Name)
							return
						}
						subName = composite
					}
					name = field.Schema.namer.IndexName(
						field.Schema.Table, subName)
				}

	cacheStmt := Stmt{Transaction: isTransaction, prepared: make(chan struct{})}
	db.Stmts[query] = &cacheStmt
	db.Mux.Unlock()

	// prepare completed
	defer close(cacheStmt.prepared)

	// Reason why cannot lock conn.PrepareContext
	// suppose the maxopen is 1, g1 is creating record and g2 is querying record.
	// 1. g1 begin tx, g1 is requeue because of waiting for the system call, now `db.ConnPool` db.numOpen == 1.

func (i *Num) Scan(src interface{}) error {
	switch s := src.(type) {
	case []byte:
		n, _ := strconv.Atoi(string(s))
		*i = Num(n)
	case int64:
		*i = Num(s)
	default:
		return errors.New("Cannot scan NamedInt from " + reflect.ValueOf(src).String())
	}
	return nil
}

type StringsSlice []string

func (l StringsSlice) Value() (driver.Value, error) {
	bytes, err := json.Marshal(l)