来自多个WITH / CTE的多个插入

Question

我有一张这样的桌子：

CREATE TABLE mytable
(
  col1 character varying(50),
  mydate timestamp without time zone
);

我想向该表中插入数据，但我也想存储源中的最大id：

insert into mytable (select myid, col1, mydate from sourcetable);

我的mytable中没有myid列，以后也不能再问这样的事情： select max(myid) from sourcetable因为我正在获取快照，并且sourcetable是一个事务表（每秒数百条新记录） ），因此我需要从该快照获取最大ID

我尝试过这样的事情：

with query1 as (select myid, col1, mydate from sourcetable),
query2 as (select max(myid) id from query1)
insert into mytable (select co1, mydate from query1);
update anothertable set value=(select myid from query2) where col2='avalue';

但是我得到这个错误：

ERROR:  relation "query2" does not exist
LINE 1: update anothertable set value=(select myid from query2) wher...

有办法解决吗？

Answer 1

问题是您在CTE之后有两个查询。 只有一个。 CTE连接到查询。 因此，只需添加另一个CTE。 像这样：

with query1 as (
      select myid, col1, mydate
      from sourcetable
     ),
     query2 as (
      select max(myid) as id
      from query1
     ),
     i as (
      insert into mytable   -- You should really list the columns here
          select co1, mydate
          from query1
     )
update anothertable
    set value = (select myid from query2)
    where col2 = 'avalue';