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[数据库]SQL Server之纵表与横表互转


1,纵表转横表

纵表结构 Table_A:

转换后的结构:

纵表转横表的SQL示例:

SELECT  Name ,
        SUM(CASE WHEN Course = N'语文' THEN Grade
                 ELSE 0
            END) AS Chinese ,
        SUM(CASE WHEN Course = N'数学' THEN Grade
                 ELSE 0
            END) AS Mathematics ,
        SUM(CASE WHEN Course = N'英语' THEN Grade
                 ELSE 0
            END) AS English
FROM    dbo.Table_A
GROUP BY Name

2,横表转纵表

横表结构Table_B:

转换后的表结构:

横表转纵表的SQL示例:

SELECT  Name ,
        'Chinese' AS Course ,
        Chinese AS Score
FROM    dbo.Table_B
UNION ALL
SELECT  Name ,
        'Mathematics' AS Course ,
        Mathematics AS Score
FROM    dbo.Table_B
UNION ALL
SELECT  Name ,
        'English' AS Course ,
        English AS Score
FROM    dbo.Table_B
ORDER BY Name ,
        Course DESC