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mysql如何去除两个字段数据相同的记录

方法有很多,这里介绍两种 方法一、如果要保留id的最小值,例如: 数据:执行sql:select count(*) as count ,name,id from ceshi group by name<img 最后要删除的sql为:delete from ceshi where id not in (select count(*) as count ,n...

MySQL查询重复字段,及删除重复记录的方法 数据库中有个大表,需要查找其中的名字有重复的记录id,以便比较。如果仅仅是查找数据库中name不重复的字段,很容易: SELECT min(`id`),`name` FROM `table` GROUP BY `name`; 但是这样并不能得到说有重...

select name,grade,testGrade,count(*) from t_student group by (name,grade,testGrade) having count(*)>1 where grade is null

假设表名为test: select * from (select *, concat(name,code) as __f from test order by date desc) __t group by __f;

MySQL查询重复字段,及删除重复记录的方法 数据库中有个大表,需要查找其中的名字有重复的记录id,以便比较。如果仅仅是查找数据库中name不重复的字段,很容易: SELECT min(`id`),`name` FROM `table` GROUP BY `name`; 但是这样并不能得到说有重...

比如你的表有销量sale和价格price delete from 表明 where sale=price;删除销量字段里面和价格里面相同数据的行

思路: 1.先查询一样的数据 select * from table where num1 in(select num2 from table); 2.进行删除 delete table where id in(select id from table where num1 in(select num2 from table));

做一个group by 保留其中id 最大的(你说自增长 id最大的应该就是最新的)就可以 具体sql query 可以这样写 delete from test where id not in( select name,email,max(id) from test group by name,email having id is not null)

假设表名为test: 1 select * from (select *, concat(name,code) as __f from test order by date desc) __t group by __f;

Distinct 去除重复 Test 字段去重如下 select distinct Test from Table

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