在一列連接多個行

Question

我有產生以下結果

NAME   WeekPattern 

John Smith 
John Smith // 
John Smith OO 
Jack Jones 
Jack Jones O 
Jack Jones // 

查詢有沒有一種方法我可以連接的WeekPattern列，這樣的結果將顯示如下：

NAME   WeekPattern 

John Smith  // OO 
Jack Jones  O // 

我曾嘗試使用FOR XML PATH但無法使其正常工作，下面是查詢我的嘗試：

SELECT 
p.p_surname, 
p.p_forenames, 
LEFT(sr.sr_weekpattern , LEN(sr.sr_weekpattern)-1) AS Weekpattern 
FROM 
unitesnapshot.dbo.capd_studentregister sr 
INNER JOIN unitesnapshot.dbo.capd_person p ON p.p_id = sr.sr_student 
CROSS APPLY 
(
    SELECT sr.sr_weekpattern + ' ' 
    FROM unitesnapshot.dbo.capd_studentregister sr1 
    INNER JOIN unitesnapshot.dbo.capd_person p1 ON p1.p_id = sr1.sr_student 

    WHERE p.p_id = p1.p_id 
    FOR XML PATH('') 
) pre_trimmed (Weekpattern) 
GROUP BY p.p_surname, p.p_forenames, sr.sr_weekpattern; 

運行此查詢時出現此錯誤：

傳遞給LEFT或SUBSTRING函數的長度參數無效。

任何幫助會根據您現有的查詢非常感激

Answer 1

，你是不是在LEFT引用正確的列，你應該用：

SELECT 
    p.p_surname, 
    p.p_forenames, 
    LEFT(pre_trimmed.Weekpattern , LEN(pre_trimmed.Weekpattern)-1) AS Weekpattern 
FROM unitesnapshot.dbo.capd_studentregister sr 
INNER JOIN unitesnapshot.dbo.capd_person p 
    ON p.p_id = sr.sr_student 
CROSS APPLY 
(
    SELECT sr1.sr_weekpattern + ' ' 
    FROM unitesnapshot.dbo.capd_studentregister sr1 
    INNER JOIN unitesnapshot.dbo.capd_person p1 
    ON p1.p_id = sr1.sr_student 
    WHERE p.p_id = p1.p_id 
    FOR XML PATH('') 
) pre_trimmed (Weekpattern) 

Answer 2

SELECT 
    Name, 
    STUFF(
     (SELECT ' ' + WeekPattern 
      FROM TableName 
      WHERE NAME = a.NAME AND WeekPattern IS NOT NULL 
      FOR XML PATH ('')) 
      , 1, 1, '') AS WeekPatternList 
FROM TableName AS a 
GROUP BY Name 

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