SQL语句来判断数据库某一列下是否有相同值的记录方法

楼主您好

select

max(sum)

from(

select

该列,count(1)

sum

from

table

group

by

该列

having

count(1)>1)

如果结果大于1，则表示存在相同记录

CREATE TABLE message (

id int,

name1 varchar(2),

data1 int,

name2 varchar(2),

data2 int

);

INSERT INTO message

SELECT 1, 'A', 4, 'A', 1 UNION ALL

SELECT 2, 'B', 3, 'C', 2 UNION ALL

SELECT 3, 'A', 3, 'B', 4 UNION ALL

SELECT 4, 'B', 2, 'D', 6 UNION ALL

SELECT 5, 'C', 5, 'A', 4 UNION ALL

SELECT 6, 'A', 4, 'C', 7 UNION ALL

SELECT 7, 'A', 5, 'A', 8 UNION ALL

SELECT 8, 'B', 9, 'A', 3 UNION ALL

SELECT 9, 'B', 7, 'B', 4 UNION ALL

SELECT 10, 'C', 8, 'C', 5;

SELECT

my_data,

CONCAT('(', GROUP_CONCAT(my_name), ')') AS names

FROM

(

SELECT 'name1' as my_name, data1 as my_data FROM message WHERE name1 = 'A'

UNION

SELECT 'name2' as my_name, data2 as my_data FROM message WHERE name2 = 'A'

) subQuery

GROUP BY

my_data

ORDER BY

my_data DESC;

+---------+---------------+

| my_data | names |

+---------+---------------+

| 8 | (name2) |

| 5 | (name1) |

| 4 | (name1,name2) |

| 3 | (name1,name2) |

| 1 | (name2) |

+---------+---------------+

5 rows in set (000 sec)

以上就是关于SQL语句来判断数据库某一列下是否有相同值的记录方法全部的内容，包括:SQL语句来判断数据库某一列下是否有相同值的记录方法、SQL数据库，select两个字段的非重复值并且排序、等相关内容解答，如果想了解更多相关内容，可以关注我们，你们的支持是我们更新的动力！