这个问题在这里已经有答案了:
如何在mysql中进行完整的外部连接(15个答案)
两年前关门了。
这是下面的一个问题,用sum和count连接两个表。我试图做的是将所有值显示为历史表中的一些值,而不是rota表中的值,反之亦然(999和777)
所以我的table是:
create table history (
code int(10) primary key,
PN varchar(10) not null,
Qty int(10) not null,
LOC_ID int(10));
insert into history values (1, 'T1', 1, 1);
insert into history values (2, 'A1', 2,2);
insert into history values (3, 'J1', 3,3);
insert into history values (4, 'A2', 1,4);
insert into history values (5, 'J2', 2,1);
insert into history values (6, 'A3', 3,2);
insert into history values (7, 'J3', 4,3);
insert into history values (8, 'T1', 5,4);
insert into history values (9, 'A1', 1,1);
insert into history values (10, '999', 3,2);
insert into history values (11, 'J2', 4,3);
insert into history values (12, 'A1', 3,4);
insert into history values (13, 'J2', 5,1);
create table rota (
code int(10) primary key,
PN varchar(10) not null,
SN varchar(10) not null,
LOC_ID int(10));
insert into rota values (1, 'T1', 't1a',1);
insert into rota values (2, 'A1', 'a1a',2);
insert into rota values (3, 'J1', 'j1a',3);
insert into rota values (4, 'A2', 'a2a',4);
insert into rota values (5, 'J2', 'j2a',1);
insert into rota values (6, 'A3', 'a3a',2);
insert into rota values (7, 'J3', 'j3a',3);
insert into rota values (8, '777', 't1b',4);
insert into rota values (9, 'A1', 'a1b',1);
insert into rota values (10, 'J2', 'j2b',2);
insert into rota values (11, 'J2', 'j2c',3);
insert into rota values (12, 'A1', 'a1c',4);
insert into rota values (13, 'J2', 'j2d',1);
insert into rota values (14, 'J2', 'j2e',2);
insert into rota values (15, 'J2', 'j2f',3);
create table loca (
code1 int(10) primary key,
LOC varchar(10) not null);
insert into loca values (1, 'AAA');
insert into loca values (2, 'BBB');
insert into loca values (3, 'CCC');
insert into loca values (4, 'DDD');
我得到的密码是
select CASE WHEN a.pn IS NULL THEN b.pn ELSE a.pn END AS PN
, a.q
, b.c
, a.LOC_ID
, b.LOC_ID
from
(select
h.pn
, sum(qty) q
, h.LOC_ID
from
history h
group by h.pn, h.LOC_ID) a
RIGHT JOIN
(select
r.pn
, count(sn) c
, r.LOC_ID
from
rota r
group by r.pn, r.LOC_ID) b
on a.pn = b.pn WHERE a.LOC_ID = b.LOC_ID
order by a.pn;
上面的代码对于两个表中的所有pn都非常有效。问题是特定于其中一个表的值。我可以从join中删除where子句,但它不正确。问题是-如何从历史和罗塔那里得到所有的pn,其中一些是存在的,我只需要一张table。我很幸运地使用了right join,但这并没有涵盖另一个表中的唯一值。以前有人遇到过解决办法吗?
结果如下表所示
PN LOC_ID Count Qty
T1 1 1 1
A1 2 1 2
J1 3 1 3
A2 4 1 1
J2 1 2 2
A3 2 1 3
J3 3 1 4
777 4 1 NULL
A1 1 1 1
J2 2 2 NULL
J2 3 2 4
A1 4 1 3
J2 1 2 2
J2 2 2 NULL
J2 3 2 4
999 2 NULL 3
1条答案
按热度按时间6ioyuze21#
使用另一个连接,即
left
让他们union
```select t.PN,t.q,t.c,t.LOC_ID,t.LOC_ID_b from
(
select CASE WHEN a.pn IS NULL THEN b.pn ELSE a.pn END AS PN
, a.q
, b.c
, a.LOC_ID
, b.LOC_ID as LOC_ID_b
from
(select
h.pn
, sum(qty) q
, h.LOC_ID
from
history h
group by h.pn, h.LOC_ID) a
RIGHT JOIN
(select
r.pn
, count(sn) c
, r.LOC_ID
from
rota r
group by r.pn, r.LOC_ID) b
on a.pn = b.pn and a.LOC_ID = b.LOC_ID
) as t
union
select t2.PN,t2.q,t2.c,t2.LOC_ID,t2.LOC_ID_b from
(
select CASE WHEN a.pn IS NULL THEN b.pn ELSE a.pn END AS PN
, a.q
, b.c
, a.LOC_ID
, b.LOC_ID as LOC_ID_b
from
(select
h.pn
, sum(qty) q
, h.LOC_ID
from
history h
group by h.pn, h.LOC_ID) a
left JOIN
(select
r.pn
, count(sn) c
, r.LOC_ID
from
rota r
group by r.pn, r.LOC_ID
) b
on a.pn = b.pn and a.LOC_ID = b.LOC_ID
) t2