MySql: ”Commands out of sync“Error (Connect/C++)

使用 Connector/C++ 查询 Mysql ， 连续调用存储过程时

会出现如下：

Commands out of sync; you can't run this command now,state:HY000

 

出现原因可以看这里：http://stackoverflow.com/questions/17115919/mysql-commands-out-of-sync-error-c-connector

这一句：

Because CALL can return multiple results, process them using a loop that calls mysql_next_result() to determine whether there are more results. "

Connector/C++ 封装后，使用  getMoreResults() 函数来读取下一个 resultset;

例子如下：

　　　　 // 查询存储过程
        prepareState.reset(con->prepareStatement("call test.testproc1(?)"));
        prepareState->setInt(1,1001);
        prepareState->executeUpdate();

        result.reset(prepareState->getResultSet());
        // 输出结果    
        while(result->next())
        {
            int id = result->getInt("id");
            string name = result->getString("name");
        }

        while(prepareState->getMoreResults())                            //注意这里, 调用 getMoreResults() 把所有的 resultset读出来
        {
            result.reset(prepareState->getResultSet());
            
            //对下一组result set 做某些东西
        }
　　　　　　
        prepareState.reset(con->prepareStatement("call test.testproc3(?)"));
        prepareState->setInt(1,1001);
        prepareState->executeUpdate();

        result.reset(prepareState->getResultSet());
        // 输出结果    
        while(result->next())
        {
            int id = result->getInt("id");
            string name = result->getString("name");
        }

        while (prepareState->getMoreResults())
            result.reset(prepareState->getResultSet());