如何使用SQL查詢將行中的列帶入？

Question

使用此查詢后，得到以下結果：

select SCHOOL_YEAR,COUNT(MUSIC) as ct,MUSIC from [table1]
group by SCHOOL_YEAR,MUSIC;

SCHOOL_YEAR   ct      MUSIC

2011          100     Piano
2011          50      Violin
2012          70      Piano
2012          150     Violin

我想要以下格式：

SCHOOL_YEAR   Piano     Violin

2011           100        50
2012           70         150

我該如何實現？

Answer 1

在原始表格上使用數據透視查詢，但僅在學年進行匯總：

SELECT
    SCHOOL_YEAR,
    SUM(CASE WHEN MUSIC = 'Piano'  THEN 1 ELSE 0 END) AS Piano,
    SUM(CASE WHEN MUSIC = 'Violin' THEN 1 ELSE 0 END) AS Violin
FROM table1
GROUP BY
    SCHOOL_YEAR