sql - 如何使用连接查询一列中有多个值的表

Question

表 1:

A       B       C
Test    1       This
Test1   1;4     That
Test2   7       What
Test3   6;2     Which
Test4   1;2;7   Where

表 2:

X       Z
1       Sun
2       Mon
3       Tue
4       Wed
5       Thu
6       Fri
7       Sat

SQL:

Select
    t1.A,
    t2.Z
from
    [dbo].[Table 1] t1
    inner join [dbo].[Table2] t2
    on t1.B = t2.X

它仅适用于 B 列中只有 1 个条目的行，但在 2 个或更多条目时失败。

如何修改 Sql 以便它给出如下结果:

A       Z
Test    Sun
Test1   Sun;Wed
Test2   Sat
Test3   Fri;Mon
Test4   Sun;Mon;Sat

Answer 1

字符串和 XML 的乐趣，这里有一个用于标记数据的小(缩小)技术。

创建一些示例数据

Declare @Table1 table (A varchar(100),B varchar(100), C varchar(100))
Insert Into @Table1 values
('Test','1','This'),('Test1','1;4','That'),('Test2','7','What'),('Test3','6;2','Which'),('Test4','1;2;7','Where')

Declare @Table2 table (X int,Z varchar(100))
Insert Into @Table2 values
(1,'Sun'),(2,'Mon'),(3,'Tue'),(4,'Wed'),(5,'Thu'),(6,'Fri'),(7,'Sat')

<小时/>

SQL

Declare @XML xml,@Str varchar(max) = (Select a,z='['+replace(b,';','];[')+']' From  @Table1 For XML Raw)
Select @Str = Replace(@Str,'['+cast(X as varchar(25))+']',Z) From  @Table2
Select @XML = @Str

Select a = r.value('@a','varchar(100)')
      ,z = r.value('@z','varchar(100)')
From  @XML.nodes('/row') as A(r)

返回

a       z
Test    Sun
Test1   Sun;Wed
Test2   Sat
Test3   Fri;Mon
Test4   Sun;Mon;Sat