Mysql 标记新值和重复值的代码

Question

我有一个 mysql table（如下所示）有一些值，我需要获取新值和重复值

我试过了SELECT *,COUNT(SerialNumber) FROM config_log GROUP BY SerialNumber；

但它 return 只有重复计数。如何找到这个？？？

谢谢

Table :

   Id   SerialNumber   ConfigDate  ProductId
    ---+--------------+-----------+---------
    1    11111          2018-12-22    1
    2    22222          2018-12-22    2
    3    33333          2018-12-22    3
    4    11111          2018-12-23    1

产品Table：

 ProductId    Name
-----------+------
  1           a
  2           b
  3           c

预期结果

Id   SerialNumber   ConfigDate   Type      Name
---+--------------+------------+----------+-------
1    11111          2018-12-22   New          a
2    22222          2018-12-22   New          b
3    33333          2018-12-22   New          c
4    11111          2018-12-23   Duplicate    a

Answer 1

您可以尝试以下 -

DEMO

select id,SerialNumber,ConfigDate, case when num=1 then 'New' else 'Duplicate' end as  Type,
productid,name
from
(
SELECT 
    @row_number:=CASE
        WHEN @SerialNumber = SerialNumber THEN @row_number + 1
        ELSE 1
    END AS num,
    @SerialNumber:=SerialNumber as PSerialNumber, id, SerialNumber,ConfigDate,productid,name
FROM
    t1 left join product on productid=pid ,(SELECT @SerialNumber:=0,@row_number:=0) AS t
order by SerialNumber
)A

Answer 2

以下 mysql 查询将产生预期结果

SELECT cl.*, 
       IF (cl.id = (SELECT Min(id) 
                    FROM   `config_log` 
                    WHERE  cl.serialnumber = serialnumber 
                    ORDER  BY id ASC), 'NEW', 'DUPLICATE') AS type, 
       p.name 
FROM   `config_log` AS `cl` 
       INNER JOIN products AS p 
               ON p.id = cl.productid

已在 mysql Distrib 5.7.24 上针对 Linux (x86_64)

进行测试

Answer 3

过滤结果你可以使用这样的

SELECT cl.*, 
       IF (cl.id = (SELECT Min(id) 
                    FROM   `config_log` 
                    WHERE  cl.serialnumber = serialnumber 
                    ORDER  BY id ASC), 'NEW', 'DUPLICATE') AS type, 
       p.name 
FROM   `config_log` AS `cl` 
       INNER JOIN products AS p 
               ON p.id = cl.productid 
HAVING type = 'DUPLICATE'

Mysql 标记新值和重复值的代码

Mysql Code To Mark New And Duplicate Values

mysql

stored-procedures

select-query