具有多列连接的 Sql 查询

Posted 2023-02-24

【中文标题】具有多列连接的 Sql 查询

【英文标题】：Sql query with multiple column join

【发布时间】：2014-03-09 01:07:58

【问题描述】：

我遇到了一个问题：

表1

C1   C2    C3  tempId
1    4      5    ab
2    6      7    fc 
3    8      9    vb

表2

ids    val
1       a
2       b
3       c
4       d
5       e
6       f
7       g
8       h
9       i

我想传递 tempId 的值，即 ab 并希望输出类似

valofc1 valofc2 valofc3 
a          d      e

请帮助我不知道如何实现。

【问题讨论】：

在哪个RDBMS ????是用于 SQL Server 还是 mysql 还是 SQLIte

【参考方案1】：

试试这个方法：

select t21.val as valofc1, t22.val as valofc2, t23.val as valofc3 
from table1 as t
join table2 as t21 on t21.ids = t.C1
join table2 as t22 on t22.ids = t.C2
join table2 as t23 on t23.ids = t.C3
where t.tempId = 'ab'

【参考方案2】：

试试这个

   select t2.val valofc1,t3.val valofc2,t4.val valofc3 from table1 t1
   inner join table2 t2 on t1.C1 = t2.ids
   inner join table2 t3 on t1.C2 = t3.ids
   inner join table2 t4 on t1.C3 = t4.ids
   where tempId = 'ab'

DEMO HERE

【参考方案3】：

Declare @t table (C1 int,C2 int,C3 int,tempId varchar(50))
insert into @t values (1,4,5,'ab'),(2,6,7,'fc'),(3,8,9,'vb')
Declare @table2 table (id int,val varchar(50))
insert into @table2 values(1,'a'),(2,'b'),(3,'c'),(4,'d'),(5,'e'),(6,'f'),(7,'g'),(8,'h'),(9,'i')
select 
(select val from @table2 where id=t.C1)valofc1 ,
(select val from @table2 where id=t.C2)valofc2,
(select val from @table2 where id=t.C3)valofc3
from @t t where tempid='ab'