多次插入WITH/CTE

Question

我有这样的一个表：

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

我希望将数据插入到这个表，也是我想最大的ID从我的源存储：

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

我在mytable中没有myid列，后来我不能再问这样的问题：select max(myid) from sourcetable，因为我得到一个快照，而sourcetable是一个事务表（每秒有数百个新记录），所以我需要从该快照中获取最大ID

我想是这样的：

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... 

有没有办法解决这个问题的方法吗？

Answer 1

问题是，你有两个查询CTE后的。只有一个。 CTE连接到查询。所以，只需添加另一个CTE。事情是这样的：

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';