根据列 B 的值连接列 A - SQL Server [重复]答案

【问题标题】：Concatenate Column A depending on Value of Column B - SQL Server [duplicate]根据列 B 的值连接列 A - SQL Server [重复]
【发布时间】：2016-06-22 17:06:15
【问题描述】：

I have a table that looks like the following


COLUMN_A|| COLUMN_B ||
======================
NAME1   ||    1     ||
NAME2   ||    1     ||
NAME3   ||    1     ||  
NAME4   ||    2     ||  
NAME5   ||    2     ||  
NAME6   ||    3     ||
NAME7   ||    3     ||

我想根据 COLUMN_B 连接 COLUMN_A。如果 COLUMN_B 的值相同，则 COLUMN_A 应以逗号分隔。

预期结果

NAME1, NAME2, NAME3
NAME4, NAME5
NAME6, NAME7

【问题讨论】：

标签： sql-server tsql sql-server-2012

【解决方案1】：

Declare @Table table (id int,Name varchar(25))
Insert Into @Table values 
(1,'NAME1'),
(1,'NAME2'),
(1,'NAME3'),
(2,'NAME4'),
(2,'NAME5'),
(3,'NAME6'),
(3,'NAME7')



SELECT 
  [ID],
  STUFF((
    SELECT ', ' + NAME 
    FROM @Table
    WHERE (ID = Results.ID) 
    FOR XML PATH(''),TYPE).value('(./text())[1]','VARCHAR(MAX)')
  ,1,2,'') AS NAME
FROM @Table Results
GROUP BY ID

ID  NAME
1   NAME1, NAME2, NAME3
2   NAME4, NAME5
3   NAME6, NAME7

【讨论】：

【解决方案2】：

您可以使用递归来帮助解决此问题：

CREATE TABLE #Temp(ColumnA VARCHAR(50), ColumnB INT)

INSERT INTO #Temp 
VALUES('NAME1', 1)
, ('NAME2', 1)
, ('NAME3', 1)
, ('NAME4', 2)
, ('NAME5', 2)
, ('NAME6', 3)
, ('NAME7', 3)

;WITH Numbered 
AS
(
SELECT ColumnA, ColumnB, ROW_NUMBER() OVER (PARTITION BY ColumnB ORDER BY ColumnA) AS RowNum
FROM #Temp 
)
,RecordCounts
AS
(
SELECT ColumnB, COUNT(1) AS RecordCount
FROM #Temp
GROUP BY ColumnB
)
,RecursiveCTE
AS
(
SELECT ColumnB, CONVERT(VARCHAR(50), ColumnA) AS ColumnA, RowNum
FROM Numbered 
WHERE RowNum = 1
UNION ALL
SELECT N.ColumnB, CONVERT(VARCHAR(50), R.ColumnA + ', ' + N.ColumnA), N.RowNum
FROM RecursiveCTE R 
    INNER JOIN Numbered N ON R.ColumnB = N.ColumnB 
        AND N.RowNum = R.RowNum + 1
)
SELECT ColumnA 
FROM RecursiveCTE R
INNER JOIN RecordCounts RC ON R.ColumnB = RC.ColumnB
    AND R.RowNum = RC.RecordCount 
ORDER BY R.ColumnB

DROP TABLE #Temp

【讨论】：