mysql - 比较 Drupal 中的 2 个字段

Question

我想在 Drupal 中做一个简单的 SQL 查询，但我不确定如何做。我想实现这一目标:

SELECT COUNT(nid) AS i_count FROM node WHERE `created` != `changed`;

我有以下代码，它不起作用:

$query = db_select('node', 'n');
$query->addExpression("COUNT(nid)","i_count");
$query->condition("created","changed","!=");
$i_number_published = $query->execute()->fetchCol();

它不起作用的原因是它将列created 与字符串值"changed" 进行比较。有什么方法可以告诉它比较列而不是列字符串？

Answer 1

使用where()成员函数根据表中其他字段添加条件:

$query = db_select('node', 'n');
$query->addExpression("COUNT(nid)","i_count");
$query->where("created != changed");
$i_number_published = $query->execute()->fetchCol();