Question

我的列表就像[1,2,3,2,5,2] 所需结果是2次发生3次。我正在使用mysql存储过程。我试图在mysql中找到设置。

Answer 1

使用aggregation和group by

select no, count(*)
from tablename
group by no

Answer 2

如果只需要重复的值，请尝试

SELECT num, COUNT(num) AS c FROM yourTable GROUP BY num HAVING c>1

Answer 3

一个技巧是替换列表中的2并对照之前的大小检查大小。（尽管我怀疑您的列表可能不止一位数字）

例如

set @a = '1,2,3,5,2,6';

select  length(@A) ,
            length(replace(@a,'2','')),
            length(@A) - length(replace(@a,'2','')) 

+------------+----------------------------+-----------------------------------------+
| length(@A) | length(replace(@a,'2','')) | length(@A) - length(replace(@a,'2','')) |
+------------+----------------------------+-----------------------------------------+
|         11 |                          9 |                                       2 |
+------------+----------------------------+-----------------------------------------+
1 row in set (0.00 sec)

如果数字的长度不同，则将差值除以搜索项的长度

set @a = '1,2,11,12,13,15,12,16,12,100';
set @b = '12';
select  length(@A) ,
            length(replace(@a,@b,'')),
            (length(@A) - length(replace(@a,@b,''))) / length(@b);

+------------+---------------------------+-------------------------------------------------------+
| length(@A) | length(replace(@a,@b,'')) | (length(@A) - length(replace(@a,@b,''))) / length(@b) |
+------------+---------------------------+-------------------------------------------------------+
|         28 |                        22 |                                                3.0000 |
+------------+---------------------------+-------------------------------------------------------+
1 row in set (0.00 sec)

如何在Mysql存储过程的列表中查找重复/重复值？

3 个答案: