php - 如何按字段下订单但里面有条件？

Question

请高手，我有三个表，我需要从中选择数据LEFT JOIN；并且我需要按字段q（存在于 中table3）进行排序，但仅在 state = 1 的地方（也存在于 中table3）。

我试过这个但它不起作用：

SELECT * FROM table 1
         LEFT JOIN table2 ON x = y
         LEFT JOIN table3 ON z=w
         WHERE w = 1
         ORDER BY q IN ( SELECT q FROM table3 WHERE state = 1);

请问有什么建议吗？

Answer 1

这是怎么回事：

SELECT * FROM table 1
         LEFT JOIN table2 ON x = y
         LEFT JOIN table3 ON z=w
         WHERE w = 1
         ORDER BY case when state=1 then 0 else 1 end,q 

Answer 2

试试这个：

SELECT *,
    (SELECT q FROM table3 WHERE state = 1) as sort_order
FROM table 1
    LEFT JOIN table2 ON x = y
    LEFT JOIN table3 ON z=w
WHERE w = 1
ORDER BY sort_order

因为我不知道期望的结果应该是什么，所以这可能是正确的查询：

SELECT *
FROM table1 as t1
    LEFT JOIN table2 as t2 ON t1.x = t2.y
    LEFT JOIN table3 as t3 ON t2.z = t3.w AND t3.state = 1
WHERE t3.w = 1
ORDER BY t3.q

Answer 3

尝试这样的事情：

SELECT * FROM table 1
         LEFT JOIN table2 ON x = y
         LEFT JOIN table3 ON z=w
         WHERE w = 1 AND table3.state = 1
         ORDER BY q