MySQL INSERT INTO inside UPDATE 和 SET new primary key as foreign key

Question

我有一个 table，其中一些引用的 datastores 已被删除，并且它们的外键引用为空。我需要插入一个新的 datastore 并在引用中设置外键 table.

所有 ID 都是 UUIDs，我的伪查询看起来像这样但不起作用：

UPDATE `rcachievements_player_achievements`
SET data_id = (INSERT INTO `rcachievements_datastore` (data) VALUES ('{"count":0}'))
WHERE data_id is null

有什么方法可以插入 datastore，然后在 data_id 字段中为缺少数据存储的每一行设置 id？

Answer 1

您必须将其作为多个查询来执行。首先将新行插入 rcachievements_datastore，然后更新所有引用行。

SET @id = UUID();
INSERT INTO `rcachievements_datastore` (id, data) VALUES (@id, '{"count":0}');

UPDATE `rcachievements_player_achievements`
SET data_id = @id
WHERE data_id is null;

Answer 2

我最终用 FOR LOOP 完成了它，如下所示：

DELIMITER //

FOR i IN (SELECT id FROM `rcachievements_player_achievements` WHERE data_id is NULL)
DO
        SET @id = UUID();
        INSERT INTO `rcachievements_datastore` (id, data, version, when_created, when_modified) VALUES (@id, '{"count":0}', 1, CURRENT_TIMESTAMP(), CURRENT_TIMESTAMP());
        UPDATE `rcachievements_player_achievements` SET data_id = @id WHERE id = i.id;
END FOR;
//

DELIMITER ;

SELECT id FROM `rcachievements_player_achievements` WHERE data_id is NULL;

MySQL INSERT INTO inside UPDATE 和 SET new primary key as foreign key

MySQL INSERT INTO inside UPDATE and SET new primary key as foreign key

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