一列保存多個(gè)ID(將多個(gè)用逗號(hào)隔開的ID轉(zhuǎn)換成用逗號(hào)隔開的名稱)_Mssql數(shù)據(jù)庫(kù)教程
推薦:經(jīng)典SQL語(yǔ)句大全一、基礎(chǔ) 1、說(shuō)明:創(chuàng)建數(shù)據(jù)庫(kù) CREATE DATABASE database - name 2、說(shuō)明:刪除數(shù)據(jù)庫(kù) drop database dbname 3、說(shuō)明:備份sql server -- - 創(chuàng)建 備份數(shù)據(jù)的 device USE master EXEC sp_addumpdevice ' disk ' , ' testBack ' , ' c:\mssql7backup\MyNwind_1.dat ' --
背景:在做項(xiàng)目時(shí),經(jīng)常會(huì)遇到這樣的表結(jié)構(gòu)在主表的中有一列保存的是用逗號(hào)隔開ID。如,當(dāng)一個(gè)員工從屬多個(gè)部門時(shí)、當(dāng)一個(gè)項(xiàng)目從屬多個(gè)城市時(shí)、當(dāng)一個(gè)設(shè)備從屬多個(gè)項(xiàng)目時(shí),很多人都會(huì)在員工表中加入一個(gè)deptIds VARCHAR(1000)列(本文以員工從屬多個(gè)部門為例),用以保存部門編號(hào)列表(很明顯這不符合第一范式,但很多人這樣設(shè)計(jì)了,在這篇文章中我們暫不討論在這種應(yīng)用場(chǎng)景下,如此設(shè)計(jì)的對(duì)與錯(cuò),有興趣的可以在回復(fù)中聊聊),然后我們?cè)诓樵兞斜碇行枰吹竭@個(gè)員工從屬哪些部門。初始化數(shù)據(jù):
部門表、員工表數(shù)據(jù):
- IF EXISTS (SELECT * FROM sys.objects WHERE object_id = OBJECT_ID(N'[dbo].[Department]'))
- DROP TABLE [dbo].Department
- GO
- --部門表
- CREATE TABLE Department
- (
- id int,
- name nvarchar(50)
- )
- INSERT INTO Department(id,name)
- SELECT 1,'人事部'
- UNION
- SELECT 2,'工程部'
- UNION
- SELECT 3,'管理部'
- SELECT * FROM Department
- IF EXISTS (SELECT * FROM sys.objects WHERE object_id = OBJECT_ID(N'[dbo].[Employee]'))
- DROP TABLE [dbo].Employee
- GO
- --員工表
- CREATE TABLE Employee
- (
- id int,
- name nvarchar(20),
- deptIds varchar(1000)
- )
- INSERT INTO Employee(id,name,deptIds)
- SELECT 1,'蔣大華','1,2,3'
- UNION
- SELECT 2,'小明','1'
- UNION
- SELECT 3,'小華',''
- SELECT * FROM Employee
希望得到的結(jié)果:
解決方法:
第一步,是得到如下的數(shù)據(jù)。即將員工表集合與相關(guān)的部門集合做交叉連接,其中使用了fun_SplitIds函數(shù)(作用是將ids分割成id列表),然后員工集合與這個(gè)得到的集合做交叉連接
SELECT E.*,ISNULL(D.name,'') AS deptName FROM Employee AS E OUTER APPLY dbo.fun_SplitIds(E.deptIds) AS DID LEFT JOIN Department AS D ON DID.ID=D.id;
第二步,已經(jīng)得到了如上的數(shù)據(jù),然后要做的就是根據(jù)ID分組,并對(duì)deptName列做聚合操作,但可惜的是SQL SERVER還沒有提供對(duì)字符串做聚合的操作。但想到,我們處理樹形結(jié)構(gòu)數(shù)據(jù)時(shí),用CTE來(lái)做關(guān)系數(shù)據(jù),做成有樹形格式的數(shù)據(jù),如此我們也可以將這個(gè)問(wèn)題轉(zhuǎn)換成做樹形格式的問(wèn)題,代碼如下:
結(jié)果如下:
- WITH EmployeT AS(
- --員工的基本信息(使用OUTER APPLY將多個(gè)ID拆分開來(lái),然后與部門表相關(guān)聯(lián))
- --此時(shí)已將員工表所存的IDS分別與部門相關(guān)聯(lián),下面需要將此集合中的deptName聚合成一個(gè)記錄
- SELECT E.*,ISNULL(D.name,'') AS deptName
- FROM Employee AS E
- OUTER APPLY dbo.fun_SplitIds(E.deptIds) AS DID
- LEFT JOIN Department AS D ON DID.ID=D.id
- ),mike AS(
- SELECT id,name,deptIds,deptName
- ,ROW_NUMBER()OVER(PARTITION BY id ORDER BY id) AS level_num
- FROM EmployeT
- ),mike2 AS(
- SELECT id,name,deptIds,CAST(deptName AS NVARCHAR(100)) AS deptName,level_num
- FROM mike
- WHERE level_num=1
- UNION ALL
- SELECT m.id,m.name,m.deptIds,CAST(m2.deptName+','+m.deptName AS NVARCHAR(100)) AS deptName,m.level_num
- FROM mike AS m
- INNER JOIN mike2 AS m2 ON m.ID=m2.id AND m.level_num=m2.level_num+1
- ),maxMikeByIDT AS(
- SELECT id,MAX(level_num) AS level_num
- FROM mike2
- GROUP BY ID
- )
- SELECT A.id,A.name,A.deptIds,A.deptName
- FROM mike2 AS A
- INNER JOIN maxMikeByIDT AS B ON A.id=B.ID AND A.level_num=B.level_num
- ORDER BY A.id OPTION (MAXRECURSION 0)
全部SQL:
- IF EXISTS (SELECT * FROM sys.objects WHERE object_id = OBJECT_ID(N'[dbo].[Department]'))
- DROP TABLE [dbo].Department
- GO
- --部門表
- CREATE TABLE Department
- (
- id int,
- name nvarchar(50)
- )
- INSERT INTO Department(id,name)
- SELECT 1,'人事部'
- UNION
- SELECT 2,'工程部'
- UNION
- SELECT 3,'管理部'
- SELECT * FROM Department
- IF EXISTS (SELECT * FROM sys.objects WHERE object_id = OBJECT_ID(N'[dbo].[Employee]'))
- DROP TABLE [dbo].Employee
- GO
- --員工表
- CREATE TABLE Employee
- (
- id int,
- name nvarchar(20),
- deptIds varchar(1000)
- )
- INSERT INTO Employee(id,name,deptIds)
- SELECT 1,'蔣大華','1,2,3'
- UNION
- SELECT 2,'小明','1'
- UNION
- SELECT 3,'小華',''
- SELECT * FROM Employee
- --創(chuàng)建一個(gè)表值函數(shù),用來(lái)拆分用逗號(hào)分割的數(shù)字串,返回只有一列數(shù)字的表
- IF EXISTS (SELECT * FROM sys.objects WHERE object_id = OBJECT_ID(N'[dbo].[fun_SplitIds]'))
- DROP FUNCTION [dbo].fun_SplitIds
- GO
- CREATE FUNCTION dbo.fun_SplitIds(
- @Ids nvarchar(1000)
- )
- RETURNS @t_id TABLE (id VARCHAR(36))
- AS
- BEGIN
- DECLARE @i INT,@j INT,@l INT,@v VARCHAR(36);
- SET @i = 0;
- SET @j = 0;
- SET @l = len(@Ids);
- while(@j < @l)
- begin
- SET @j = charindex(',',@Ids,@i+1);
- IF(@j = 0) set @j = @l+1;
- SET @v = cast(SUBSTRING(@Ids,@i+1,@j-@i-1) as VARCHAR(36));
- INSERT INTO @t_id VALUES(@v)
- SET @i = @j;
- END
- RETURN;
- END
- GO
- ;WITH EmployeT AS(
- --員工的基本信息(使用OUTER APPLY將多個(gè)ID拆分開來(lái),然后與部門表相關(guān)聯(lián))
- --此時(shí)已將員工表所存的IDS分別與部門相關(guān)聯(lián),下面需要將此集合中的deptName聚合成一個(gè)記錄
- SELECT E.*,ISNULL(D.name,'') AS deptName
- FROM Employee AS E
- OUTER APPLY dbo.fun_SplitIds(E.deptIds) AS DID
- LEFT JOIN Department AS D ON DID.ID=D.id
- ),mike AS(
- SELECT id,name,deptIds,deptName
- ,ROW_NUMBER()OVER(PARTITION BY id ORDER BY id) AS level_num
- FROM EmployeT
- ),mike2 AS(
- SELECT id,name,deptIds,CAST(deptName AS NVARCHAR(100)) AS deptName,level_num
- FROM mike
- WHERE level_num=1
- UNION ALL
- SELECT m.id,m.name,m.deptIds,CAST(m2.deptName+','+m.deptName AS NVARCHAR(100)) AS deptName,m.level_num
- FROM mike AS m
- INNER JOIN mike2 AS m2 ON m.ID=m2.id AND m.level_num=m2.level_num+1
- ),maxMikeByIDT AS(
- SELECT id,MAX(level_num) AS level_num
- FROM mike2
- GROUP BY ID
- )
- SELECT A.id,A.name,A.deptIds,A.deptName
- FROM mike2 AS A
- INNER JOIN maxMikeByIDT AS B ON A.id=B.ID AND A.level_num=B.level_num
- ORDER BY A.id OPTION (MAXRECURSION 0)
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- 相關(guān)鏈接:
復(fù)制本頁(yè)鏈接| 搜索一列保存多個(gè)ID(將多個(gè)用逗號(hào)隔開的ID轉(zhuǎn)換成用逗號(hào)隔開的名稱)
- 教程說(shuō)明:
Mssql數(shù)據(jù)庫(kù)教程-一列保存多個(gè)ID(將多個(gè)用逗號(hào)隔開的ID轉(zhuǎn)換成用逗號(hào)隔開的名稱)。