连接表上的 SQL 更新查询

Question

UPDATE 
    t1
SET 
    t1.c3 = t2.c3,
    t1.c4 = t1.c4 
FROM 
    t1
    LEFT JOIN t2 ON t1.c1 = t2.c1 AND t1.c2 = t2.c2
WHERE 
    t1.c5 = 'In Progrss'

我想从表 t2 的第一行更新值。

例如，在 t2 表中，有 3 行的条件匹配仅高于顶行值update in t1 table(ROW ID 3 VALUES TO UPDATE IN t1 table)。

t2 表：

id  c1      c2     c3     c4
-----------------------------
1   ABC     XYZ    280    300
2   ABC     XYZ    290    400
3   ABC     XYZ    310    500
4   PQR     STR    210    400

t1 表：

id  c1      c2     c3     c4   c5
----------------------------------
1   ABC     XYZ                In Progrss
5   ABC     XYZ                In Progrss
8   ABC     XYZ                In Progrss
15  PQR     STR                IN Progress

Answer 1

Postgres 的更新/加入语法如下：

update t1
set c3 = t2.c3, c4 = t1.c4
from t2
where 
    t1.c1 = t2.c1 
    and t1.c2 = t2.c2
    and t1.c5 = 'In Progress'

如果t2 中有多个匹配行，而您想要id 最小的行，则可以在子查询中使用row_number()：

update t1
set c3 = t2.c3, c4 = t1.c4
from (select t2.*, row_number() over(partition by c1, c2 order by id) rn from t2) t2
where 
    t1.c1 = t2.c1 
    and t1.c2 = t2.c2
    and t1.c5 = 'In Progress'
    and t2.rn = 1