我希望我的输出如下所示：
我的要求如下：
最新服务编号
默认='Y'
我应该如何编写查询？有人能帮我吗？
最佳答案
您可以使用此：
select se.svcid, p1.pname as serviceprovider, p2.pname as tmidprovider
from tmid t
inner join (select sno, max(svcid) as maxsvcid from service group by sno) s
on t.sno = s.sno and t.`default` = 'Y'
inner join service se on se.svcid = s.maxsvcid
left join provider p1 on se.pid = p1.pid
left join provider p2 on t.pid = p2.pid;
表
create table service (svcid int, sno varchar(20), pid int);
insert into service values
(1, '11-11-11-11', 1), (2, '11-11-11-11', 2), (3, '11-11-11-12', 1), (4, '11-11-11-12', 2), (5, '11-11-11-13', NULL);
create table tmid (id int, sno varchar(20), pid int, `default` char(1));
insert into tmid values
(1, '11-11-11-11', 1, 'N'),(2, '11-11-11-11', 2, 'Y'),(3, '11-11-11-12', 1, 'N'),
(4, '11-11-11-12', 2, 'Y'),(5, '11-11-11-13', 2, 'Y'),(6, '11-11-11-13', 3, 'N');
create table provider (pid int, pname varchar(20));
insert into provider values (1, 'Ambank'), (2, 'Citybank'), (3, 'CIMB Bank');
数据
mysql> select * from service;
+-------+-------------+------+
| svcid | sno | pid |
+-------+-------------+------+
| 1 | 11-11-11-11 | 1 |
| 2 | 11-11-11-11 | 2 |
| 3 | 11-11-11-12 | 1 |
| 4 | 11-11-11-12 | 2 |
| 5 | 11-11-11-13 | NULL |
+-------+-------------+------+
mysql> select * from tmid;
+------+-------------+------+---------+
| id | sno | pid | default |
+------+-------------+------+---------+
| 1 | 11-11-11-11 | 1 | N |
| 2 | 11-11-11-11 | 2 | Y |
| 3 | 11-11-11-12 | 1 | N |
| 4 | 11-11-11-12 | 2 | Y |
| 5 | 11-11-11-13 | 2 | Y |
| 6 | 11-11-11-13 | 3 | N |
+------+-------------+------+---------+
mysql> select * from provider;
+------+-----------+
| pid | pname |
+------+-----------+
| 1 | Ambank |
| 2 | Citybank |
| 3 | CIMB Bank |
+------+-----------+
结果
+-------+-----------------+--------------+
| svcid | serviceprovider | tmidprovider |
+-------+-----------------+--------------+
| 2 | Citybank | Citybank |
| 4 | Citybank | Citybank |
| 5 | NULL | Citybank |
+-------+-----------------+--------------+