error:2014 Commands out of sync; you can't run this command now

时间:2024-09-24 16:03:26

如下错误:

error:2014 Commands out of sync; you can't run this command now

分析原因: 前端ajax请求后台,共用同一个链接。

搜索别人的解决方案:http://blog.****.net/grass_ring/article/details/3499402

 用mysql C API 调用存储过程,并返回结果集。需要注意几个问题:
在建立链接的时候要加选项CLIENT_MULTI_STATEMENTS 或 CLIENT_MULTI_RESULTS,以便可以让query执行多个语句。
mysql_real_connect(mySQL,serverIP,user,password,database,serverPort,NULL,CLIENT_MULTI_STATEMENTS)
当query时可能产生错误error: Commands out of sync; you can't run this command now Mysql文档中说明错误:Commands out of sync
If you get Commands out of sync; you can't run this command now in your client code, you are calling client functions in the wrong order.
This can happen, for example, if you are using mysql_use_result() and try to execute a new query before you have called mysql_free_result(). It can also happen if you try to execute two queries that return data without calling mysql_use_result() or mysql_store_result() in between. 当执行完query后,mysql将结果集放在一个result集中,产生以上问题的原因有两个:
一是未将MYSQL_RES所指对象释放,即在下次查询时要mysql_free_result();
二是结果result集不为空,这个原因比较隐蔽。解决方法可以用如下写法:
do
{
/* Process all results */
printf("total affected rows: %lld", mysql_affected_rows(mysql));
...
if (!(result= mysql_store_result(mysql)))
{
printf(stderr, "Got fatal error processing query/n");
exit();
}
process_result_set(result); /* client function */
mysql_free_result(result);
} while (!mysql_next_result(mysql));
还有个问题感觉比较奇怪,我调用一个存储过程,存储过程中就一句select
Create procedure test()
Begin
Select * from test ;
End ;
用以上方法处理结果集循环会执行两次,开始我只调了一次result= mysql_store_result(mysql)),导致以后执行query报2014错误。

最终,我为每个请求,建立一个connection,并且在使用完毕后,就主动释放。