Question

我有一张桌子，我正在处理这些句柄＆＃34;门票＆＃34; （状态=＆＃34;打开＆＃34;或状态=＆＃34;关闭＆＃34;）。当故障单关闭时，系统会创建一个重复的条目，而不是更改状态，而是关闭＆＃34;关闭＆＃34;状态。

使用＆＃34; ticket_number＆＃34;的关键字段，如何修改下面的查询以忽略任何状态=＆＃34;打开＆＃34;如果是另一条记录，则为＃34; ticket_number＆＃34;字段存在＆＃34;关闭＆＃34;状态？

我无法使用＆＃34; DISTINCT＆＃34;而且我对如何根据字段值从查询中有选择地过滤（接近）重复记录感到有点迷失。

感谢您的帮助。

SELECT (@cnt := @cnt + 1) AS item_number, t.*
FROM test t
CROSS JOIN (SELECT @cnt := 0) AS dummy
WHERE created >= DATE_SUB(CURDATE(), INTERVAL 7 DAY)
AND created<= NOW()
ORDER BY created_at DESC

Answer 1

您需要将列表放入查询中以进行交叉连接。将其用作FROM语句，或将其实现为临时表并在FROM中使用它。

SELECT * FROM(
     select a.*, b.status as closedstatus
     from test.tickets a
     left join (select ticketid, status from test.tickets where status='closed') b on a.ticketid=b.ticketid
    where a.status='open') t
WHERE closedstatus is null

Answer 2

如果数据中有某些内容标识了故障单状态更改的顺序，例如自动增量ID字段或日期，那么您可以选择上一个状态事件，例如

drop table if exists t;
create table t(id int auto_increment primary key,ticket_number int, status varchar(6));

insert into t (ticket_number,status) values
(1,'open'),(2,'open'),(2,'closed'),(3,'open'),(3,'closed'),(3,'open'),
(4,'open'),(4,'closed'),(4,'open'),(4,'closed');

select * 
from t 
where id = (select max(t1.id) from t t1 where t1.ticket_number = t.ticket_number)
        and t.status = 'open';
MariaDB [sandbox]> select *
    -> from t
    -> where id = (select max(t1.id) from t t1 where t1.ticket_number = t.ticket_number)
    -> and t.status = 'open';

+----+---------------+--------+
| id | ticket_number | status |
+----+---------------+--------+
|  1 |             1 | open   |
|  6 |             3 | open   |
+----+---------------+--------+
2 rows in set (0.00 sec)

MySQL基于字段值忽略（近）重复

2 个答案: