PDO内存耗尽

Question

这是常见的问题,但我没有选择像这样编码只是为了在Excel文件中获得适当的标题和正文

它是如何开始的

当请求打印时,我首先开始查询以获取数据库中的标头

SELECT instruments.in_id, instrument_parameters.ip_id,
CASE WHEN gv_x_ipid = -1 THEN 'datetime' ELSE '' END xlabel,
CASE WHEN ip_label LIKE '%Reservoir%' THEN 0 ELSE in_order END legendIndex,
CASE WHEN in_name = 'General' THEN ip_label ELSE in_name END ylabel            
FROM graph_plot
LEFT JOIN attributes gptype ON gp_type = gptype.at_id
LEFT JOIN graph_value ON gp_id = gv_gpid
LEFT JOIN instrument_parameters ON gv_y_ipid = ip_id
LEFT JOIN attributes pmunit ON ip_unit = pmunit.at_id
LEFT JOIN instrument_reading yvalue ON gv_y_ipid = iv_ipid
LEFT JOIN instruments ON iv_inid = in_id
WHERE gp_diid = :di_id AND 
      gp_type = :rpt_type AND 
      iv_status = 'Y' AND
      iv_inid in (".implode(",", $coll->inid).") AND
      gv_y_ipid in (".implode(",", $coll->ipid).")
GROUP BY ylabel
ORDER BY legendIndex

这将产生数量的标题,我将使它像这样

DATE | Instrument1 | Instrument2 | Instrument3

在Instrument?将基于上面的查询是动态的.我将它存储在新变量中.但保存数据库结果的原始变量保持不变.

后来,使用相同的参数,:di_id并且:rpt_type,还另有其他参数,startDt并endDt再作查询只是返回数据库可用日期一长串.这是基于startDt和endDt.

$sql2 = "SELECT iv_reading FROM instrument_reading WHERE iv_inid = :inid AND iv_ipid = :ipid AND iv_date = :dt AND iv_status = 'Y'";    

当它完成日期后,我做了两个这样的循环

foreach ($dates as $key => $dt) {       
    foreach ($resp as $InstNo => $InstRow) {
        try {
            $stmt2->execute(array(':dt' => $dt, ':inid' => $InstRow->in_id, ':ipid' => $InstRow->ip_id));
            $rowDb = $stmt2->fetch(PDO::FETCH_NUM, PDO::FETCH_ORI_NEXT);
        } catch(PDOException $e) {
            echo '{"error":{"text":"'. $e->getMessage() .'"}}'; 
        }
    }
}

首先,它开始循环日期,然后开始循环标题(基于在获取日期之前进行的查询).我的问题我一直都在这里

$stmt2->execute(array(':dt' => $dt, ':inid' => $InstRow->in_id, ':ipid' => $InstRow->ip_id));

你怎么看？有没有更好的方法来处理这个？

为了您的信息,我使用Slim和PHPExcel.PHPExcel可能有内存问题,我想切换到Spout,但文档仍然是关于基本的东西.

Answer 1

在SQL中,您可以考虑使用limit子句来减轻内存负载,如下所示:

$handle = fopen("file.csv", "wb");
$statement = "
SELECT  instruments.in_id, instrument_parameters.ip_id,
       CASE WHEN gv_x_ipid = -1 THEN 'datetime' ELSE '' END xlabel,
       CASE WHEN ip_label LIKE '%Reservoir%' THEN 0 ELSE in_order END legendIndex,
       CASE WHEN in_name = 'General' THEN ip_label ELSE in_name END ylabel
    FROM  graph_plot
    LEFT JOIN  attributes gptype ON gp_type = gptype.at_id
    LEFT JOIN  graph_value ON gp_id = gv_gpid
    LEFT JOIN  instrument_parameters ON gv_y_ipid = ip_id
    LEFT JOIN  attributes pmunit ON ip_unit = pmunit.at_id
    LEFT JOIN  instrument_reading yvalue ON gv_y_ipid = iv_ipid
    LEFT JOIN  instruments ON iv_inid = in_id
    WHERE  gp_diid = :di_id
      AND  gp_type = :rpt_type
      AND  iv_status = 'Y'
      AND  iv_inid in (".implode(",", $coll->inid).")
      AND  gv_y_ipid in (".implode(",", $coll->ipid).")
    GROUP BY  ylabel
    ORDER BY  legendIndex
    LIMIT  250
";
$prep = $dbh->prepare($statement);
for ($i = 0; $prep -> rowCount < 250; $i+= 250) {
    fputcsv(prep->fetchAll());
    $prep = $dbh->prepare($statement.' OFFSET'.$i);
}
fclose($handle);

或者,您可以使用系统并调用SELECT INTO,设置权限(如果需要),Bob是您的叔叔.

Answer 2

你还没有终止fetch循环.

$rowDb = $stmt2->fetch(PDO::FETCH_NUM, PDO::FETCH_ORI_NEXT);

获取"下一行"或关闭"光标"并终止.

你期待得到一排吗？如果是这样,请考虑进行fetchAll.(注意:结果集可能是数组中的额外级别.)