MySql: 」Commands out of sync「Error (Connect/C++)

使用 Connector/C++ 查詢 Mysql ， 連續調用存儲過程時

會出現以下：

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

 

出現緣由能夠看這裏：http://stackoverflow.com/questions/17115919/mysql-commands-out-of-sync-error-c-connector

這一句：

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++ 封裝後，使用  getMoreResults() 函數來讀取下一個 resultset;

例子以下：

　　　　 // 查詢存儲過程
        prepareState.reset(con->prepareStatement("call test.testproc1(?)"));
        prepareState->setInt(1,1001);
        prepareState->executeUpdate();

        result.reset(prepareState->getResultSet());
        // 輸出結果    
        while(result->next())
        {
            int id = result->getInt("id");
            string name = result->getString("name");
        }

        while(prepareState->getMoreResults())                            //注意這裏, 調用 getMoreResults() 把全部的 resultset讀出來
        {
            result.reset(prepareState->getResultSet());
            
            //對下一組result set 作某些東西
        }
　　　　　　
        prepareState.reset(con->prepareStatement("call test.testproc3(?)"));
        prepareState->setInt(1,1001);
        prepareState->executeUpdate();

        result.reset(prepareState->getResultSet());
        // 輸出結果    
        while(result->next())
        {
            int id = result->getInt("id");
            string name = result->getString("name");
        }

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