sql 使用子查询更新多行

Question

我正在尝试将对应的毕业日期值从毕业术语表复制到 user_education_mba_school 表中具有匹配的毕业术语 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

-- 多重连接不起作用...

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

一些数据库支持

update ... from

语法，这是相当清晰的：

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，请说明您正在使用哪个数据库。

Answer 2

这不起作用，因为您正在设置子查询的整个结果集

UPDATE user_education_mba_school SET graduation_date = (
  SELECT gt.graduation_date
  FROM user_education_mba_school mba, graduation_term gt
  WHERE gt.graduation_term_id = mba.graduation_term_id
)

这应该有效（未经测试）

UPDATE user_education_mba_school mba SET graduation_date = (
  SELECT gt.graduation_date
  FROM graduation_term gt
  WHERE gt.graduation_term_id = mba.graduation_term_id
)

Answer 3

UPDATE  mba
SET     graduation_date = gt.graduation_date, mba_graduation_year_id = gt.graduation_year_id
FROM    user_education_mba_school mba
JOIN    [sueldovista].dbo.graduation_term gt
ON      gt.graduation_term_id = mba.graduation_term_id


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    [sueldovista].dbo.graduation_term gt
ON      mba.graduation_term_id = gt.graduation_term_id
JOIN    [sueldovista].dbo.graduation_class gc
ON      gt.graduation_year_id = gc.graduation_year_id
WHERE   gc.site_instance_id = 1

Answer 4

甲骨文：

UPDATE PRODUCTION a
SET (name, count) = (
  SELECT name, count
  FROM STAGING b
  WHERE a.ID = b.ID);

Answer 5

如果您的子查询有多行，请使用 IN

UPDATE db1
SET
field = 1
WHERE id IN (
SELECT id
FROM db2
LEFT JOIN db3
ON db2.id = db3.id
WHERE db3.id IS NOT NULL
)