SQL 将结果集从列表转换为网格

Question

我有以下结果集，它是两个连接表的结果，我想使用子查询重新定向结果。这是当前结果集的示例，它是动态记录数：

Forename    Surname    Subject      Result
Mercury     Freddie    English      C
Mercury     Freddie    Mathematics  D
Simon       Paul       English      E
Simon       Paul       Mathematics  F
Garfunkle   Art        English      A
Garfunkle   Art        Mathematics  B

这就是我想要实现的目标：

Forename    Surname    English    Mathematics  
Mercury     Freddie    C          D
Simon       Paul       E          F
Garfunkle   Art        A          B

我尝试使用 case 语句来填充它，但这会导致以下结果：

Forename    Surname    English    Mathematics  
Mercury     Freddie    NULL
Simon       Paul       NULL
Garfunkle   Art        NULL
Mercury     Freddie    C          NULL
Simon       Paul       E          NULL
Garfunkle   Art        A          NULL

Answer 1

你可以

使用CASE，你只需要将它与一些聚合函数（如MAX()和GROUP BY

SELECT 
 Forename, Surname
 , MAX(CASE WHEN SUBJECT = 'English' THEN Result END) AS English 
 , MAX(CASE WHEN SUBJECT = 'Mathematics' THEN Result END) AS Mathematics 
FROM Table1
GROUP BY Forename, Surname

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