AI摘要
文章介绍了如何使用SQL查询和删除数据库中重复的type数据，首先通过分组和筛选找出重复的type及其最小id，然后通过子查询确定需要删除的非最小id记录。由于MySQL不能直接删除查询结果，需借助临时表实现删除操作。最终通过删除非最小id的记录，保留每个type的最小id数据。
查出重复的type
SELECT type FROM table GROUP BY type HAVING count(type) > 1;
查出重复的type数据中最小的id
SELECT min(id) FROM table GROUP BY type HAVING count(type) > 1;
查出重复的type数据中非最小的id(需要删除的)
SELECT id FROM table WHERE type in(
SELECT type FROM table GROUP BY type HAVING count(type) > 1)
AND id not IN(SELECT min(id) FROM table GROUP BY type HAVING count(type) > 1);
在Mysql中是不能删除查询出来的记录，而是要通过一张临时表来解决
SELECT id from (
SELECT id FROM table WHERE type in(
SELECT type FROM table GROUP BY type HAVING count(type) > 1)
AND id not IN(SELECT min(id) FROM table GROUP BY type HAVING count(type) > 1)
) as t;
删除type重复的数据(只保留一条，保留最小id的)
DELETE FROM table WHERE id IN (
SELECT id from (
SELECT id FROM table WHERE type in(
SELECT type FROM table GROUP BY type HAVING count(type) > 1)
AND id not IN(SELECT min(id) FROM table GROUP BY type HAVING count(type) > 1)
) as t
);
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最后更新: 2025-12-23
