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行列转换就是如下图所示两种展示形式的互相转换

假如我们有下表：

SELECT name,  MAX(  CASE    WHEN subject='语文'    THEN score    ELSE 0  END) AS "语文",  MAX(  CASE    WHEN subject='数学'    THEN score    ELSE 0  END) AS "数学",  MAX(  CASE    WHEN subject='英语'    THEN score    ELSE 0  END) AS "英语"FROM studentGROUP BY name

通过上面 SQL 语句即可得到下面的结果

列转行

假设我们有下表

SELECT    NAME,    '语文' AS subject ,    MAX("语文") AS scoreFROM student1 GROUP BY NAMEUNIONSELECT    NAME,    '数学' AS subject ,    MAX("数学") AS scoreFROM student1 GROUP BY NAMEUNIONSELECT    NAME,    '英语' AS subject ,    MAX("英语") AS scoreFROM student1 GROUP BY NAME

通过上面 SQL 语句即可得到下面的结果

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