mysql 删除重复数据 mysql 4 不支持嵌套的删除语法， 因此得需要通过创建临时表绕过

delete.sql

DROP TABLE IF EXISTS tmp_dels;

CREATE TABLE tmp_dels AS SELECT subscribe_tags.id FROM subscribe_tags, ( SELECT max(id) AS id, nick, tag_id FROM subscribe_tags GROUP BY nick, tag_id HAVING count(1) > 1 ) t WHERE subscribe_tags.nick = t.nick AND subscribe_tags.tag_id = t.tag_id AND subscribe_tags.id < t.id;

DELETE FROM subscribe_tags WHERE id IN (SELECT id FROM tmp_dels);

DROP TABLE IF EXISTS tmp_dels;