• SQLServer行转列


    近期面试遇到了一道面试题。顿时有点迷糊,仅仅说出了思路。后来百度了一下。整理了一下思路,于是记录下来,方便以后学习。(面试题请參见附件)

    相关的数据表:

    1.Score表

    2.[User]表

    SQL语句例如以下:

    --方法一:静态SQL
    SELECT * FROM
    (SELECT UID,Name, Score,ScoreName FROM Score,[User] WHERE Score.UID=[User].ID) AS SourceTable
    PIVOT(AVG(Score)FOR ScoreName IN ([英语], [数学])) AS a

    --方法二:动态SQL
    DECLARE @s NVARCHAR(4000)  
    SELECT @s = ISNULL(@s + ',', '') +  QUOTENAME(ScoreName)  
    FROM  (select distinct ScoreName from Score) as A ---列名不要反复  

    Declare @sql NVARCHAR(4000)  
    SET @sql='  
     select r.* from  
    (select UID,Name,ScoreName,Score from Score,[User] where Score.UID=[User].ID) as t  
    pivot  
    (  
    max(t.Score)  
    for t.ScoreName in ('+@s+')  
    ) as r'  
    EXEC( @sql)

    --方法三:Case When
    select  
      row_number() OVER(ORDER BY [User].ID) as 编号,
      UID as 用户编号,
      Name as 姓名,
      max(case ScoreName when '英语' then Score else 0 end) 英语,
      max(case ScoreName when '数学' then Score else 0 end) 数学
    from Score,[User] WHERE Score.UID=[User].ID
    group by UID,[User].ID,Name

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  • 原文地址:https://www.cnblogs.com/zfyouxi/p/5132848.html
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