mysql 如何去重
数据表:
sql代码:
delete FROM test where id NOT in( select id FROM tmp )
create table tmp (select id FROM test GROUP BY `name` )
tmp是创建的临时表,不需要提前创建,直接写接好,
为什么要创建临时表,看下面:
直接写会报错 :
delete FROM test where id NOT in( select id FROM test GROUP BY `name` )
[SQL]
delete FROM test where id NOT in( select id FROM test GROUP BY `name` )
[Err] 1093 – You can\’t specify target table \’test\’ for update in FROM clause
要先运行create table tmp (select id FROM test GROUP BY `name` )
先创建临时表,才能查询