Question

我目前是学生，我正在努力解决SQL的一个小问题。我想基于同一个表中的过滤结果对表执行更新语句。 Here is the table I have:

这是我到目前为止的查询：

UPDATE ComplexityLessons
SET ACADEMYRATIO = '0,896' 
WHERE (
    SELECT c.START, c.DATE, c.ACTIVITY, c.ACADEMY
from ComplexityLessons c
join (
    SELECT b.ACTIVITY, b.START, b.DATE
    FROM ComplexityLessons b
) as b 
on c.ACTIVITY = b.ACTIVITY and c.DATE = b.DATE and c.START = b.START
having COUNT(DISTINCT ACADEMY) = 2)

总而言之，我想更新专栏＆＃34; ActivityRatio＆＃34;只有2个学院同时开展相同活动的地方。当我只使用子查询时，我得到了同时执行相同活动的学院，但我无法弄清楚更新语句。预先感谢您的帮助！

Answer 1

UPDATE ComplexityLessons SET ACADEMYRATIO = '0,896' 
WHERE ( SELECT c.START, c.DATE, c.ACTIVITY, c.ACADEMY 
        from ComplexityLessons c 
join ( SELECT b.ACTIVITY, b.START, b.DATE 
       FROM ComplexityLessons b ) as b 
on c.ACTIVITY = b.ACTIVITY and c.DATE = b.DATE and c.START = b.START 
having COUNT(DISTINCT ACADEMY) = 2)

应该具有条件的位置和子查询应该返回id。例如

UPDATE ComplexityLessons SET ACADEMYRATIO = '0,896'
WHERE <id> in ( SELECT <id> from ComplexityLessons c 
join ( SELECT b.ACTIVITY, b.START, b.DATE 
       FROM ComplexityLessons b ) as b 
on c.ACTIVITY = b.ACTIVITY and c.DATE = b.DATE and c.START = b.START 
having COUNT(DISTINCT ACADEMY) = 2)

应该是表之间的foriegn键。

带有子查询的SQL Update语句，在where子句中使用相同的表

1 个答案: