解决mysql数据重复问题-只保留一条数据

<pre name="code" class="html">1.sql语句,原理使用临时表法，效率比较低delete  FROM `source`  WHERE is_deleted=0          AND (student_id,score_id) IN      (SELECT f.student_id ,           f.score_id      FROM          (SELECT b.`student_id` AS student_id ,           b.`score_id` AS score_id          FROM `source` b          WHERE b.`is_deleted`=0          GROUP BY  b.student_id,b.score_id          HAVING count(*) > 1) f )              AND id NOT IN      (SELECT g.id      FROM          (SELECT min(c.id) AS id          FROM `source` c          WHERE c.`is_deleted`=0          GROUP BY  c.`student_id`,c.`score_id`          HAVING count(*)>1) g );2.临时表法-需要dba协作1.停服情况下，原表（备份），建一张临时表，将原表的唯一数据拷贝到临时表中，删除源表，更改临时表表名2.非停服情况下去重，新建一张临时表insert into temp () values (select distinct * from source)delete from source where 重复数据 in (select * from temp)insert into source () values(select * from temp)