mySQL:左连接问题

Question

我有以下查询:

 SELECT c.`entity_id`,c. p.`name` as parent_id, c.`name`
  FROM category c
  LEFT JOIN category p WHERE c.`parent_id = p.id
  WHERE c.is_active = 1
  ORDER BY c.parent_id ASC, c.position ASC;

但是我在第一个 WHERE 子句中遇到错误，有人能发现这里的错误吗？谢谢

Answer 1

您已添加 where 子句两次。请尝试如下:

SELECT c.`entity_id`,c. p.`name` as parent_id, c.`name`
FROM category c
  LEFT JOIN category p on c.`parent_id = p.id
  Where c.is_active = 1
  ORDER BY c.parent_id ASC, c.position ASC;