php - 如何创建查询以获取使用 where 子句作为结果数组索引的结果？

Question

这是我使用的查询：

$idList="32,33,21,11";          
$query = "SELECT post_id, meta_value FROM wp_posts 
          WHERE meta_key = 'grade' AND post_id IN ($idList)";

结果，where 子句成为键：

$result = array(
              0 => array('post_id'=> 32, 'meta_value'=>5),
              1 => array('post_id'=> 33, 'meta_value'=>2),
              2 => array('post_id'=> 21, 'meta_value'=>8),
           )

我希望有这样的结果：

$result = array(
              0 => array( 32 => 5 ),
              1 => array( 33 => 2 ),
              2 => array( 21 => 8 ),
           )

如何做到这一点？谢谢！

Answer 1

像这样循环结果集：

$_final = array(); // new result set

foreach ($result as $value)
  $_final[] = array($value['post_id'] => $value['meta_value']);

unset($result); // free memory from old result set

更新：如果元素太多并且您担心内存消耗，您可以通过以下方式进行操作：

$_final = array(); // new result set

foreach ($result as $key => $value) {
  $_final[] = array($value['post_id'] => $value['meta_value']); // composing new data
  unset($result[$key]); // unsetting already parsed value
}

unset($result); // freeing memory from old result set