如何在SQL Server中将多行转换为一行？

我有一个疑问。假设我有两个名为

PersonInfo

和

PersonEducation

的表。我使用

StudentId

对这些表应用了联接操作，得到了类似的结果

   StudentIdId      Name    University    Department     Status
   ---------------------------------------------------------------
      1             John    Cambridge     Computer       Graduated
      1             John    Berkeley      Mathematic     Graduated
      1             John    Boston        Economy        Ongoing

这只是一个学生的例子（约翰）。它显示约翰从两所大学毕业，仍在一所大学学习。大学人数可能会因学生而异。我的问题是如何在一行中显示这三行。我的意思是我想在一行中显示所有教育信息，以避免一个人有多行

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提前感谢您的帮助。

这取决于您对输出的要求

如果希望聚合PersonEducation中的数据以统计状态，则可以加入PersonEducation表的子查询。关于如何使用子查询和如何按字段分组的文章很多 比如：

SELECT pere.StudentId
    , pere.StudentName
    , peri.UniversityCount
    , peri.GraduatedStatusCout
    , peri.OngoingStatusCount
FROM PersonInfo peri
LEFT JOIN
    (SELECT StudentId
        , UniversityCount = COUNT(*)
        , GraduatedStatusCount = SUM(IIF(Status = 'Graduated', 1, 0))
        , OngoingStatusCount = SUM(IIF(Status = 'Ongoing', 1, 0))
    FROM PersonEducation
    GROUP BY StudentId) pere
    ON peri.StudentId = pere.StudentId;

如果你想上一所大学，那么你需要一个有日期参加的领域。有人可能同时上不止一所大学，所以你需要关于如何挑选优胜者的规则。但是，在这些情况下，可以使用子句对数据进行排序并过滤结果

您可以按照所述或在任何数量的其他文章中将数据连接在一起

测试数据 查询 结果

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你先试一试怎么样？你能给我们看一个你希望你的数据是什么样的样本吗？如果约翰在5所大学学习呢？对于任何一个学生可以拥有的大学数量是否有严格的限制？

DECLARE @TABLE TABLE (StudentIdId INT, Name VARCHAR(100), University VARCHAR(100)
                       , Department VARCHAR(100),[Status] VARCHAR(100))
INSERT INTO @TABLE VALUES 
(1 ,'John','Cambridge','Computer'  ,'Graduated'),
(1 ,'John','Berkeley' ,'Mathematic','Graduated'),
(1 ,'John','Boston'   ,'Economy'   ,'Ongoing'),
(2 ,'Pete','Cambridge','Computer'  ,'Graduated'),
(2 ,'Pete','Berkeley' ,'Mathematic','Graduated')

SELECT t.StudentIdId
      ,t.Name
      ,STUFF((SELECT ', ' + University 
              FROM @TABLE 
              WHERE StudentIdId = t.StudentIdId
              FOR XML PATH(''),TYPE).value('.','NVARCHAR(MAX)'),1,2,'') AS University
      ,STUFF((SELECT ', ' + Department 
              FROM @TABLE 
              WHERE StudentIdId = t.StudentIdId
              FOR XML PATH(''),TYPE).value('.','NVARCHAR(MAX)'),1,2,'') AS Department
      ,STUFF((SELECT ', ' + [Status] 
              FROM @TABLE 
              WHERE StudentIdId = t.StudentIdId
              FOR XML PATH(''),TYPE).value('.','NVARCHAR(MAX)'),1,2,'') AS [Status]

FROM @TABLE t 
GROUP BY t.StudentIdId ,t.Name

╔═════════════╦══════╦═════════════════════════════╦═══════════════════════════════╦═══════════════════════════════╗
║ StudentIdId ║ Name ║         University          ║          Department           ║            Status             ║
╠═════════════╬══════╬═════════════════════════════╬═══════════════════════════════╬═══════════════════════════════╣
║           1 ║ John ║ Cambridge, Berkeley, Boston ║ Computer, Mathematic, Economy ║ Graduated, Graduated, Ongoing ║
║           2 ║ Pete ║ Cambridge, Berkeley         ║ Computer, Mathematic          ║ Graduated, Graduated          ║
╚═════════════╩══════╩═════════════════════════════╩═══════════════════════════════╩═══════════════════════════════╝