在SQL Server中将行合并为字符串

假设我们需要从任何给定列表中选择所有数据。我们可以使用多个查询来组合SQL Server中的行以形成字符串。

示例1：
让我们假设下面有一个名为“ geek_demo ”的表–

FirstName	LastName	Salary	City
Ankit	Gupta	24500	Delhi
Babita	Dutta	23600	Noida
Chetan	Jain	25600	Noida
Deepak	Saini	24300	Delhi
Isha	Sharma	25900	Delhi
Khushi	Singh	24600	Noida
Megha	Goyal	25500	Noida
Parul	Kumari	23900	Noida

方法1：
在下面的示例中，我们将使用COALESCE函数合并行。

查询以串联SQL Server中的行–

DECLARE @Names VARCHAR(MAX)  
SELECT @Names = COALESCE(@Names + ', ', '') + [FirstName] 
FROM [geek_demo]
SELECT @Names AS [List of All Names]

输出 ：

List of All Names
Ankit  , Babita    , Chetan    , Deepka    , Isha      , Khushi    , Megha     , Parul

方法2：
在下面的示例中，我们还将合并姓氏行。

查询以串联SQL Server中的行–

DECLARE @FirstNames VARCHAR(MAX)
DECLARE @LastNames VARCHAR(MAX)
SELECT @FirstNames = COALESCE(@FirstNames + ', ', '') + [FirstName] 
FROM [geek_demo]   
SELECT @LastNames = COALESCE(@LastNames + ', ', '') + [LastName] 
FROM [geek_demo] 
SELECT @FirstNames AS [List of All First Names],
            @LastNames AS [List of All Last Names]

输出 ：

List of All First Names	List of All Last Names
Ankit  , Babita    , Chetan    , Deepka    , Isha      , Khushi    , Megha     , Parul	Gupta     , Dutta     , Jain      , Saini     , Sharma    , Singh     , Goyal     , Kumari

方法3：
在下面的示例中，我们还将串联姓氏行。

查询以串联SQL Server中的行–

DECLARE @FirstNames VARCHAR(MAX)
DECLARE @LastNames VARCHAR(MAX)
SELECT @FirstNames = CONCAT(@FirstNames + ', ', '') + [FirstName] 
FROM [geek_demo]  
SELECT @LastNames = CONCAT(@LastNames + ', ', '') + [LastName] 
FROM [geek_demo]
SELECT @FirstNames AS [List of First All Names],
   @LastNames AS [List of All Last Names]

输出 ：

List of First All Names	List of All Last Names
Ankit  , Babita    , Chetan    , Deepka    , Isha      , Khushi    , Megha     , Parul	Gupta     , Dutta     , Jain      , Saini     , Sharma    , Singh     , Goyal     , Kumari

方法4：
在下面的示例中，我们将使用填充函数并针对XML路径合并两列(名字和姓氏)中的行。

查询以串联SQL Server中的行–

SELECT STUFF((
   SELECT ',' + SPACE(1) + [FirstName],
   ' ' + SPACE(1) + [LastName]
 FROM [geek_demo]
  FOR XML PATH(''), TYPE).value('.', 'VARCHAR(MAX)'), 1, 1, '')
AS [List Of All Names]

输出 ：

List Of Names
Ankit   Gupta     , Babita     Dutta     , Chetan     Jain      , Deepka     Saini     , Isha       Sharma    , Khushi     Singh     , Megha      Goyal     , Parul      Kumari

示例2：
让我们假设下面有一个名为“ geek_demo1”的表–

Name	JoiningDate	Email
Ankit	04 May 2018	[e-mail]
Babita	09 July 2019	[e-mail]
Chetan	14 June 2017	[e-mail]
Deepak	26 January 2019	[e-mail]
Isha	24 May 2018	[e-mail]
Khushi	17 July 2018	[e-mail]
Megha	03 March 2017	[e-mail]
Parul	20 December 2018	[e-mail]

方法1：
在下面的示例中，我们将使用SQL Server中的CONCAT函数将行组合为字符串。

查询以串联SQL Server中的行–

DECLARE @Names VARCHAR(MAX)
DECLARE @Emails VARCHAR(MAX)
SELECT @Names = CONCAT(@Names + ', ', '') + [Name] 
FROM [geek_demo1]  
SELECT @Emails = CONCAT(@Emails + ', ', '') + [Email] 
FROM [geek_demo]  
SELECT @Names AS [List of All Names],
            @Emails AS [List of All Emails]

输出 ：

List of All Names	List of All Emails
Ankit  , Babita    , Chetan    , Deepka    , Isha      , Khushi    , Megha     , Parul	[e-mail], [e-mail], [e-mail], [e-mail], [e-mail], [e-mail], [e-mail], [e-mail]

方法2：
在下面的示例中，我们将使用SPACE和XML路径合并SQL Server中的行。

查询以串联SQL Server中的行–

SELECT STUFF((
  SELECT ',' + SPACE(1) + [Email]
  FROM [geek_demo]
  FOR XML PATH(''), TYPE).value('.', 'VARCHAR(MAX)'), 1, 1, '')
AS [List Of All Emails]

输出 ：

List Of All Emails
[e-mail], [e-mail], [e-mail], [e-mail], [e-mail], [e-mail], [e-mail], [e-mail]