PDO laststatment-> fetchAll(PDO :: FETCH_COLUMN，$ column)会在每次调用时重新运行查询吗? [英] Will PDO laststatment->fetchAll(PDO::FETCH_COLUMN, $column) rerun the query each call?

问题描述

我正在执行一个获取两个字段的查询.
我需要将每个字段放入不同的数组中.
这会为每个调用重新运行查询，还是只是对结果集进行迭代?

I am doing a query which fetches two fields.
I need each of those fields into a different array.
Will this rerun the query for each call or just re iterate over the result set?

$a= Laststatment->fetchAll(PDO::FETCH_COLUMN,0);
$b= Laststatment->fetchAll(PDO::FETCH_COLUMN,1);

推荐答案

选项3:由于已获取所有内容，因此它根本不会在结果集上重复，并且第二次调用将返回一个空数组(至少，在这里).

Option 3: it will NOT reiterate over the resultset at all, as everything already has been fetched, and the second call will return an empty array (at least, here it does).

 $a = array();
 $b = array();
 while($r = $laststatement->fetch(PDO::FETCH_NUM)){
    $a[] = $r[0];
    $b[] = $r[1];
 }

也就是说，在MySQL中没有可滚动的游标，我没有尝试使用PDO :: CURSOR_SCROLL可能性的其他数据库.

That is: with MySQL there is no scrollable cursor, I have not attempted other database with a PDO::CURSOR_SCROLL possibility.

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