1

我们正在运行一个 C 程序，其中每一秒都有一个函数回调。以下是列出的代码片段：

char timeBuf[10],secondBuf1[100],queryBuf1[500],queryBuf2[500];
char buff[20] = {0};
struct timeval tv;
gettimeofday (&tv, NULL);
tv.tv_sec -= 5;
strftime(buff, 20, "%Y-%m-%d %H:%M:%S", localtime(&tv.tv_sec));
printf("\nTime is %s", buff);

sprintf(secondBuf1,"INSERT INTO  secondsLog2 (secondLogID , timeStampID ) VALUES (NULL,'%s')",buff);
//printf("Query 1 before executing %s\n",queryBuf1);
if (mysql_query(localConn, secondBuf1)) 
{
    printf("Error in insert of seconds log %s\n",mysql_error(localConn));
    exit(1);
}

sprintf(queryBuf1,"SELECT ipDest, portDest, SUM(packetLen), COUNT(ipDest) FROM source1 WHERE timeStamp = '%s' GROUP BY portDest",buff);
printf("\nQuery buf %s",queryBuf1);
if(mysql_query(remoteConn, queryBuf1))
{
    printf("Error in first query of select %s\n",mysql_error(remoteConn));
    exit(1);
}
localRes1 = mysql_use_result(remoteConn);
while((localRow1 = mysql_fetch_row(localRes1)) !=NULL)
            {
              sprintf(queryBuf1,"INSERT INTO  export1 (iBTID ,timeStampID ,ipDest ,portDest,totalBits, packetCount) VALUES (NULL,'%s','%s','%s',%s,%s)",buff, localRow1[0],localRow1[1],localRow1[2],localRow1[3],localRow1[4]);
              printf("Query 1 before executing %s\n",queryBuf1);
              if (mysql_query(localConn, queryBuf1)) 
              {
                printf("Error in first query of insert %s\n",mysql_error(localConn));
                 exit(1);
              }

            }
                        mysql_free_result(localRes1);

在我运行这个脚本的那一刻，第二个SELECT会给我这个错误：命令不同步；您现在无法运行此命令：

Time is 2012-07-17 00:59:14
Query buf SELECT ipDest, portDest, SUM(packetLen), COUNT(ipDest) FROM source1 WHERE timeStamp = '2012-07-17 00:59:14' GROUP BY portDest
Time is 2012-07-17 00:59:15
Query buf SELECT ipDest, portDest, SUM(packetLen), COUNT(ipDest) FROM source1 WHERE timeStamp = '2012-07-17 00:59:15' GROUP BY portDestError in first query of select Commands out of sync; you can't run this command now
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1 回答 1

3

您需要清除任何将返回结果的查询的结果集。如果您不使用结果，则只需调用：

MYSQL_RES *results;
results = mysql_store_result(localConn);
mysql_free_result(results);

要使用您的结果，只需在返回结果的查询之后调用mysql_store_result(或mysql_use_result)，并确保mysql_free_result在稍后的某个时间使用它们。这应该可以清除任何CR_COMMANDS_OUT_OF_SYNC错误问题。

从mysql_store_result的文档（强调添加）：

在调用 mysql_query() 或 mysql_real_query() 之后，必须为每个成功生成结果集的语句（SELECT、SHOW、DESCRIBE、EXPLAIN、CHECK TABLE 等）调用 mysql_store_result() 或 mysql_use_result()。完成结果集后，还必须调用 mysql_free_result()。

于 2012-07-16T17:24:43.013 回答