fix: at sample (#374)

fix at rolback sample

sample/at/basic/main.go

@@ -45,16 +45,6 @@ func main() {
 	<-make(chan struct{})
 }
 
-func selectData() {
-	var orderTbl OrderTbl
-	row := db.QueryRow("select id,user_id,commodity_code,count,money,descs from  order_tbl where id = ? ", 1)
-	err := row.Scan(&orderTbl.id, &orderTbl.userID, &orderTbl.commodityCode, &orderTbl.count, &orderTbl.money, &orderTbl.descs)
-	if err != nil {
-		panic(err)
-	}
-	fmt.Println(orderTbl)
-}
-
 func updateData(ctx context.Context) error {
 	sql := "update order_tbl set descs=? where id=?"
 	ret, err := db.ExecContext(ctx, sql, fmt.Sprintf("NewDescs-%d", time.Now().UnixMilli()), 1)
@@ -68,5 +58,5 @@ func updateData(ctx context.Context) error {
 		return err
 	}
 	fmt.Printf("update success： %d.\n", rows)
-	return fmt.Errorf("test error")
+	return nil
 }