根據列B的值連接列A - SQL Server

Question

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  || 

我想根據COLUMN_B連接COLUMN_A。 如果COLUMN_B的值相同，則應該用逗號將COLUMN_A連接起來。

預期結果

NAME1, NAME2, NAME3 
NAME4, NAME5 
NAME6, NAME7 

Answer 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 

返回

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

Answer 2

您可以使用遞歸來幫助這個解決方案：

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