我有这样Table1的列：
+--+------+
|ID|Name |
+--+------+
|1 |MSSQL |
+--+------+
|2 |MySQl |
+--+------+
|3 |Oracle|
+--+------+
在Table2中，我有一个类似的列
+------------+
|Databasename|
+------------+
|1,3 |
+------------+
|2 |
+------------+
|1,2 |
+------------+
我的输出应该是：
+------------+
|Databasename|
+------------+
|MSSQL,Oracle|
+------------+
|MySQL |
+------------+
|MSSQL,MYSQL |
+------------+
我如何得到这个，我需要查询这个..
首先，您最好的解决方案是不要将数据存储在数据库中以逗号分隔的列表中。您应该考虑修复表结构。
如果您无法更改表结构，则需要将列表中的数据拆分为行以分配正确的名称。拆分数据后，您可以将数据连接回列表中。
您可以在网上找到许多不同的split功能，但这是我通常使用的一个版本：
CREATE FUNCTION [dbo].[Split](@String varchar(MAX), @Delimiter char(1))
returns @temptable TABLE (items varchar(MAX))
as
begin
declare @idx int
declare @slice varchar(8000)
select @idx = 1
if len(@String)<1 or @String is null return
while @idx!= 0
begin
set @idx = charindex(@Delimiter,@String)
if @idx!=0
set @slice = left(@String,@idx - 1)
else
set @slice = @String
if(len(@slice)>0)
insert into @temptable(Items) values(@slice)
set @String = right(@String,len(@String) - @idx)
if len(@String) = 0 break
end
return
end;
为了得到你的结果，我将首先应用split函数和 arow_number()因为我没有看到与每一行关联的唯一键。如果您在每一行上都有一个唯一键，那么您将不需要row_number()：
;with cte as
(
select rn, name, id
from
(
select row_number() over(order by (select 1)) rn,
databasename
from table2
) t2
cross apply dbo.split(t2.databasename, ',') i
inner join table1 t1
on i.items = t1.id
)
select *
from cte
此查询将您的逗号分隔列表分为以下内容：
| RN | NAME | ID |
--------------------
| 1 | MSSQL | 1 |
| 1 | Oracle | 3 |
| 2 | MySQl | 2 |
| 3 | MSSQL | 1 |
| 3 | MySQl | 2 |
一旦您拥有正确的多行数据name，您就可以使用STUFF()andFOR XML PATH将其连接到列表中。您的完整查询将与此类似：
;with cte as
(
select rn, name, id
from
(
select row_number() over(order by (select 1)) rn,
databasename
from table2
) t2
cross apply dbo.split(t2.databasename, ',') i
inner join table1 t1
on i.items = t1.id
)
select
STUFF(
(SELECT ', ' + c2.name
FROM cte c2
where c1.rn = c2.rn
order by c2.id
FOR XML PATH (''))
, 1, 1, '') Databasename
from cte c1
group by c1.rn
order by c1.rn;
完整查询的结果是：
| DATABASENAME |
------------------
| MSSQL, Oracle |
| MySQl |
| MSSQL, MySQl |
您要求使用拆分功能，但您不必拆分您的值以获得您想要的结果。
此查询使用for xml连接值的技巧在相关子查询中构建逗号分隔的名称列表。它用于确定like从.Table1Table2
select (
select ', '+T1.Name
from Table1 as T1
where ','+T2.Databasename+',' like '%,'+cast(T1.ID as varchar(10))+',%'
for xml path(''), type
).value('substring(text()[1], 3)', 'varchar(max)') as Databasenames
from Table2 as T2
没有拆分，也没有 XML 路径，但达到了正确的结果。
;with cte as (
select *, cast(null as varchar(1024)) as str, cast(0 as int) as ID
from Table2
union all
select DatabaseName, (case when DatabaseName like cast(t.ID as varchar(32)) + ',%'
or DatabaseName like '%,' + cast(t.ID as varchar(32)) + ',%'
or DatabaseName like '%,' + cast(t.ID as varchar(32))
or DatabaseName = cast(t.ID as varchar(32)) then cast(isnull(str, '') + ',' + t.Name as varchar(1024)) else str end), cte.ID + 1 as ID
from cte
inner join Table1 t on cte.ID + 1 = t.ID
)
select DatabaseName, (case when str like ',%' then substring(str, 2, len(str)) else null end) as str
from cte c
where ID = (select max(ID) from cte where DatabaseName = c.DatabaseName)
--Here it goes:
----------------
-- FieldCount --
----------------
CREATE FUNCTION [dbo].[FieldCount](@S VARCHAR(8000), @Separator VARCHAR(10))
RETURNS INT
AS
BEGIN
/*
@Author: Leonardo Augusto Rezende Santos
@Contact: http://www.linkedin.com/pub/leonardo-santos/0/2b1/890
*/
DECLARE @Ptr INT, @p INT, @LenS INT, @LenSep INT, @Result INT
IF @Separator = ' '
BEGIN
SET @S = REPLACE(@S, ' ', '|-|')
SET @Separator = '|-|'
END
WHILE CHARINDEX(@Separator + @Separator, @S) > 0
SET @S = Replace(@S, @Separator + @Separator, @Separator + '_-_' + @Separator)
IF @S <> ''
SET @Result = 1
ELSE
BEGIN
SET @Result = 0
RETURN(@Result)
END
SET @Ptr = 0
SET @LenS = LEN(@S)
SET @LenSep = LEN(@Separator)
SET @p = CHARINDEX(@Separator, @S)
WHILE @p > 0
BEGIN
SET @Result = @Result + 1
SET @Ptr = @Ptr + @p + @LenSep
SET @p = CHARINDEX(@Separator, SUBSTRING(@S, @Ptr, @LenS - @Ptr + 1))
END
RETURN(@Result)
END
--------------
-- GetField --
--------------
CREATE FUNCTION [dbo].[GetField](@S VARCHAR(8000), @Separator VARCHAR(10), @Field INT)
RETURNS VARCHAR(8000)
AS
BEGIN
/*
@Author: Leonardo Augusto Rezende Santos
@Contact: http://www.linkedin.com/pub/leonardo-santos/0/2b1/890
*/
DECLARE @Ptr INT, @p INT, @LenS INT, @LenSep INT, @Fld INT, @Result VARCHAR(8000)
IF @Separator = ' '
BEGIN
SET @S = REPLACE(@S, ' ', '|-|')
SET @Separator = '|-|'
END
IF @Field > dbo.FieldCount(@S, @Separator)
BEGIN
SET @Result = ''
RETURN(@Result)
END
SET @Fld = 1
SET @Ptr = 1
SET @LenS = LEN(@S)
SET @LenSep = LEN(@Separator)
SET @p = CHARINDEX(@Separator, @S)
WHILE (@p > 0) and (@Fld < @Field)
BEGIN
SET @Fld = @Fld + 1
SET @Ptr = @Ptr + @p + @LenSep - 1
SET @p = CHARINDEX(@Separator, SUBSTRING(@S, @Ptr, @LenS - @Ptr + 1))
END
IF (@p = 0) and (@Fld = @Field)
SET @p = @LenS - @Ptr + 2
SET @Result = SUBSTRING(@S, @Ptr, @p - 1)
RETURN(@Result)
END
/* USAGE*/
select dbo.FieldCount('A1 A2 A3 A4 A5', ' ')
--It will return 5
select dbo.GetField('A1 A2 A3 A4 A5', ' ', 3)
--It will return 'A3'
select dbo.GetField('A1/A2/A3/A4/A5', '/', 3)
--It will return 'A3'
--Hope it works for you.
--Leonardo Augusto