Mysql从具有条件和限制的另一个表INSERT INTO

Question

我有两个表有一对多关系table1（一），table2（很多）。

table1 has (t1_id) as KEY
table2 has (t2_id) as KEY and t2_t1_id as as refference to table1

现在在table1我需要一个列（ rand_t2_id ）来保存来自table2的id ，我真的不在乎哪一个

这是我试过的查询

INSERT INTO table1 (rand_t2_id)
SELECT t2_id
FROM table2
WHERE table1.t1_id = table2.t2_t1_id;

如果需要，还需要在某个地方建立限制。 我只需要table2中的一个id

这里没有运气，有人知道修复吗？

Answer 1

IMO你可以试试

UPDATE table1 t1 INNER JOIN table2 t2
  ON t1.t1_id = t2.t2_t1_id;
SET t1.rand_t2_id = t2.t2_id

我假设你的table1上已经有一个名为rand_t2_id的列。

Answer 2

INSERT INTO table1 (t2_t1_id, rand_t2_id)
SELECT t2_id
FROM (  SELECT t2_id, t2_t1_id
        FROM table2
        ORDER BY RAND()) AS h
GROUP BY t2_t1_id
ON DUPLICATE KEY UPDATE rand_t2_id = VALUES(rand_t2_id)

我想那就是你要追求的？

此查询会将随机t2_id插入到相关的table1中。