将一列包含多个ID拆分多行

看到个不常见的问题~然后在 Inner Sql Server2008 里面找到一个思路。

如果下面的表结构，如何拆分多行并对应员工号呢？

 

 

首先创建测试表

CREATE TABLE Department

(

    ID INT IDENTITY(1,1) PRIMARY KEY,

    DepartmentName VARCHAR(50) NULL,

    Members NVARCHAR(500) NULL

)



CREATE TABLE Employee

(

    ID INT IDENTITY(1,1) PRIMARY KEY,

    NAME NVARCHAR(50) NULL

)

INSERT INTO Department VALUES

('行政','1,3,5,10,12'),('销售','42,23,35,40,22'),('市场','13,17,27,28,43')

SELECT * FROM dbo.Department

 

 

Employee 表的数据直接用个 Sql Generator生成一下下就好了~

--然后搞个数字辅助表作备用

CREATE TABLE #Num (ID INT)

INSERT INTO #Num

        ( ID )

SELECT TOP 500 ROW_NUMBER() OVER (ORDER BY (SELECT 1))

 FROM sys.objects a,sys.objects b

 

 

--为了方便看代码，用个CTE来写。
;WITH CTE1 AS

(SELECT a.ID,

        a.DepartmentName,

        a.Members,

        b.ID AS Pos,

        CHARINDEX(',',a.Members,b.ID) AS NextSplit

    FROM dbo.Department a

        INNER JOIN #Num b 

            ON SUBSTRING(',' + a.Members,b.ID,1) = ','

            AND b.ID <= LEN(a.Members)

),

CTE2 AS

(SELECT ID,DepartmentName,

        CASE WHEN NextSplit <> 0 THEN SUBSTRING(Members,Pos,NextSplit - Pos)

             ELSE RIGHT(Members,LEN(Members) - Pos + 1) END AS EmployeeID

    FROM CTE1)

SELECT a.* ,b.NAME

    FROM CTE2 a

        INNER JOIN dbo.Employee b ON a.EmployeeID = b.ID

 

 

PS: 上述语句其实优化空间是很大的，这里只是提供给一个方法~就暂时不纠结效率上罗~╭(╯3╰)╮