Question

使用Postgresql（9.6），我需要根据一个选择查询的结果对任何表（ table1，table2，table3，... ）执行多个插入查询如果结果有一个或多个记录，则从另一个 tableMain 中获取，例如：

{
 insert into table1 (id, name) values(1, 'name');
 insert into table2 (id, name) values(1, 'name');
 insert into table3 (id, name) values(1, 'name');
} if exists (select id from tableMain where id = 1)

Answer 1

您可以使用data modifying CTE首先检查tablemain中的行是否存在，然后重新使用该行，以导致随后的INSERT语句。

with idcheck (main_exist) as (
  select exists (select * from tablemain where id = 1 limit 1)
), t1 as (
  insert into table1 (id, name)
  select 1, 'name'
  from idcheck 
  where main_exists
), t2 as (
  insert into table2 (id, name)
  select 1, 'name'
  from idcheck 
  where main_exists
)
insert into table3 (id, name)
select 1, 'name'
from idcheck 
where main_exists;

如果您始终想在所有三个表中插入相同的值，则可以在第一个查询中包括这些值，这样就不必重复它们：

with idcheck (id, name, main_exist) as (
  select 1, 
         'name',
         exists (select * from tablemain where id = 1 limit 1)
), t1 as (
  insert into table1 (id, name)
  select id, name
  from idcheck 
  where main_exists
), t2 as (
  insert into table2 (id, name)
  select id, name
  from idcheck 
  where main_exists
)
insert into table3 (id, name)
select id, name
from idcheck 
where main_exists;

PostgreSQL根据一次选择的结果向任何表中多次插入

1 个答案: