Question

我有一个MySQL表，它有两列id和uuid

++++++++++++++
+ ID | UUID  +
++++++++++++++
+ 74 | 3210  +
+ 75 | 3210  +
+ 76 | 3210  +
+ 77 | 3310  +
+ 78 | 3310  +
+ 79 | 3410  +
++++++++++++++

我需要使用mysql查询输出如下

+++++++++++++++
+ ID | UUID   +
+++++++++++++++
+ 74 | 3210   +
+ 75 | 3210-1 +
+ 76 | 3210-2 +
+ 77 | 3310   +
+ 78 | 3310-2 +
+ 79 | 3410   +
++++++++++++++

Answer 1

试试这个：

SELECT ID, 
       CONCAT(CAST(UUID AS CHAR(4)),
           IF(rn = 0, '', CONCAT('-', CAST(rn AS CHAR(4))))) AS UUID

FROM (
SELECT ID, UUID,
       @rn := IF(@id = UUID, @rn + 1,
                 IF(@id := UUID, 0, 0)) AS rn
FROM mytable
CROSS JOIN (SELECT @rn := 0, @id := 0) AS rn
ORDER BY UUID, ID) AS t

Demo here

Answer 2

您也可以通过提供行号来完成。

<强>查询

select t1.ID, 
(case when t1.rn > 1 
then concat(cast(t1.UUID as char(4)), '-', (t1.rn - 1))
else t1.UUID end) as UUID
from 
(
    select ID, UUID,
    (
        case UUID when @curA 
        then @curRow := @curRow + 1 
        else @curRow := 1 and @curA := UUID end 
    ) as rn 
    from my_table t, 
    (select @curRow := 0, @curA := '') r 
    order by ID 
)t1;

<强>结果

+----+--------+
| ID | UUID   |
+----+--------+
| 74 | 3210   |
| 75 | 3210-1 |
| 76 | 3210-2 |
| 77 | 3310   |
| 78 | 3310-1 |
| 79 | 3410   |
+----+--------+

SQL Fiddle demo

Answer 3

SELECT t1.ID, if(t1.rank=0, t1.uuid,concat(t1.uuid,"-",rank))
FROM 
  (
   SELECT ID, uuid,@rank := if(@uuid = uuid, @rank ,-1) + 1 rank, @uuid := uuid 
   FROM my_table,(SELECT @uuid :='', @rank :=0) vars 
   ORDER BY uuid 
  ) t1

重复记录排名

3 个答案: