SQL Server之纵表与横表互转

Posted 2020-08-09 joesphos

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