MySQL列变成行 利用max(case when then)

1. 利用max(case when then)

聚合函数，max，取最大值

 (case  when course = '语文' then score else 0 end) ---判断

as 语文---别名作为列名

 2.max(when course='语文' then score else 0 end)

mysql> SELECT
    ->  `name`,
    ->  MAX(
    ->   CASE 
    ->   WHEN course='语文' THEN
    ->    score else 0
    ->   END
    ->  ) AS 语文,
    ->  MAX(
    ->   CASE 
    ->   WHEN course='数学' THEN
    ->    score else 0
    ->   END
    ->  ) AS 数学, 
    ->  MAX(
    ->   CASE 
    ->   WHEN course='英语' THEN
    ->    score else 0
    ->   END
    ->  ) AS 英语
    -> FROM
    ->  student
    -> GROUP BY `name`
    -> ;

 参考：https://www.jb51.net/article/109487.htm

用一个例子来演示会更加清晰