diff --git a/middleware/mysql/global.go b/middleware/mysql/global.go
index 08e2369..be73b76 100644
--- a/middleware/mysql/global.go
+++ b/middleware/mysql/global.go
@@ -2,8 +2,6 @@ package mysql
 
 import (
 	"errors"
-
-	"github.com/siddontang/go-mysql/mysql"
 )
 
 var _globalPool *Pool
@@ -76,7 +74,12 @@ func Close() error {
 // Get get gets a connection from pool and validate it,
 // if there is no valid connection in the pool, it will create a new connection
 func Get() (*PoolConn, error) {
-	return _globalPool.Get()
+	conn, err := _globalPool.Get()
+	if err != nil {
+		return nil, err
+	}
+
+	return conn.(*PoolConn), nil
 }
 
 // Release releases given number of connections of global pool, each connection will disconnect with database
@@ -85,7 +88,7 @@ func Release(num int) error {
 }
 
 // Execute execute given sql statement
-func Execute(sql string, args ...interface{}) (*mysql.Result, error) {
+func Execute(sql string, args ...interface{}) (interface{}, error) {
 	if _globalPool == nil {
 		return nil, errors.New("global pool is nil, please initiate it first")
 	}
diff --git a/middleware/mysql/global_test.go b/middleware/mysql/global_test.go
index 8b66d5b..afceff9 100644
--- a/middleware/mysql/global_test.go
+++ b/middleware/mysql/global_test.go
@@ -15,7 +15,7 @@ func TestMySQLGlobalPool(t *testing.T) {
 		err       error
 		conn      *PoolConn
 		slaveList []string
-		result    *mysql.Result
+		result    interface{}
 	)
 
 	asst := assert.New(t)
@@ -43,15 +43,15 @@ func TestMySQLGlobalPool(t *testing.T) {
 	err = conn.Close()
 	asst.Nil(err, "close connection failed.")
 
-	sql := "select 1 as ok;"
-	result, err = Execute(sql)
+	sql := "select ? as ok;"
+	result, err = Execute(sql, 1)
 	asst.Nil(err, "execute sql with global pool failed.")
-	actual, err := result.GetIntByName(0, "ok")
+	actual, err := result.(*mysql.Result).GetIntByName(0, "ok")
 	asst.Nil(err, "execute sql with global pool failed.")
 	asst.Equal(int64(1), actual, "expected and actual values are not equal.")
 
 	// sleep to test maintain mechanism
-	time.Sleep(60 * time.Second)
+	time.Sleep(20 * time.Second)
 
 	err = Close()
 	asst.Nil(err, "close global pool failed.")
diff --git a/middleware/mysql/pool_test.go b/middleware/mysql/pool_test.go
index c1d0628..ea3f36d 100644
--- a/middleware/mysql/pool_test.go
+++ b/middleware/mysql/pool_test.go
@@ -8,13 +8,15 @@ import (
 	"github.com/siddontang/go-mysql/mysql"
 	"github.com/stretchr/testify/assert"
 	"go.uber.org/zap/zapcore"
+
+	"github.com/romberli/go-util/middleware"
 )
 
 func TestMySQLPool(t *testing.T) {
 	var (
 		err       error
 		pool      *Pool
-		conn      *PoolConn
+		conn      middleware.PoolConn
 		repRole   string
 		slaveList []string
 		result    *mysql.Result
@@ -38,7 +40,7 @@ func TestMySQLPool(t *testing.T) {
 	asst.Nil(err, "get connection from pool failed.")
 
 	// test connection
-	slaveList, err = conn.GetReplicationSlaveList()
+	slaveList, err = conn.(*PoolConn).GetReplicationSlaveList()
 	asst.Nil(err, "get replication slave list failed.")
 	t.Logf("replication slave list: %v", slaveList)
 
@@ -47,19 +49,19 @@ func TestMySQLPool(t *testing.T) {
 	conn, err = pool.Get()
 	asst.Nil(err, "get connection from pool failed.")
 
-	result, err = conn.GetReplicationSlavesStatus()
+	result, err = conn.(*PoolConn).GetReplicationSlavesStatus()
 	asst.Nil(err, "get replication slave status failed.")
 	if result.RowNumber() > 0 {
 		t.Logf("show slave status: %v", result.Values)
 	} else {
 		t.Logf("this is not a slave node.")
 	}
-	repRole, err = conn.GetReplicationRole()
+	repRole, err = conn.(*PoolConn).GetReplicationRole()
 	asst.Nil(err, "get replication role failed.")
 	t.Logf("replication role: %s", repRole)
 
 	// sleep to test maintain mechanism
-	time.Sleep(60 * time.Second)
+	time.Sleep(20 * time.Second)
 
 	err = pool.Close()
 	asst.Nil(err, "close pool failed.")