sql用子选择更新多行

Question

我正在尝试将 Gradation_term 表中相应的graduate_date 值复制到 user_education_mba_school 表中具有匹配gradation_term_id 的行中。这是我的非工作查询

TABLE DEFS
**user_education_mba_school
  school_id
  graduation_date
  graduation_term_id

**graduation_term
  graduation_term_id
  graduation_year_id
  graduation_date

**graduation_class
  graduation_class_id
  graduation_year_id  

**user
  user_id
  graduation_class_id

-- 多连接不工作...

UPDATE  u
SET     graduation_class_id = gc.graduation_class_id
FROM    [user] u
JOIN    user_education_mba_school mba
ON      mba.user_id = u.user_id
JOIN    graduation_term gt
ON      mba.graduation_term_id = gt.graduation_term_id
JOIN    graduation_class gc
ON      gt.graduation_year_id = gc.graduation_year_id

Answer 1

多个数据库支持 update ... from语法，这是相当清楚的:

UPDATE  mba
SET     graduation_date = gt.graduation_date
FROM    user_education_mba_school mba
JOIN    graduation_term gt
ON      gt.graduation_term_id = mba.graduation_term_id

如果您的数据库没有，请说明您使用的是哪个数据库。