Question

此代码无限期加载：

$answer_articles = $bdd->prepare(
 "SELECT * 
  FROM todo
  LEFT JOIN links_task_text
  ON links_task_text.links_task_text_id_task = todo.ID
  WHERE todo.site = ?");
$answer_articles->execute(array('xxx'));
exit();

此代码当然有效：

$answer_articles = $bdd->prepare(
 "SELECT * 
  FROM todo
  WHERE site = ?");
$answer_articles->execute(array('xxx'));
exit();

//working and no loading delays

此代码也正常运行：

$answer_articles = $bdd->prepare(
 "SELECT * FROM todo
  INNER JOIN links_task_text
  ON links_task_text.links_task_text_id_task = todo.ID
  WHERE todo.site = ?");
$answer_articles->execute(array('xxx'));
exit();

//works but it's not what I need

links_task_text.links_task_text_id_task和todo.ID是INT。

我不明白为什么左连接不起作用。一些想法？

Answer 1

列links_task_text_id_task是否有索引？

如果不是，则查询在links_task_text上运行全表扫描需要很长时间。

左连接无限加载的mysql

1 个答案: