多次插入WITH/CTE

Question

我有這樣的一個表：

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

我希望將數據插入到這個表，也是我想最大的ID從我的源存儲：

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

我在mytable中沒有myid列，後來我不能再問這樣的問題：select max(myid) from sourcetable，因爲我得到一個快照，而sourcetable是一個事務表（每秒有數百個新記錄），所以我需要從該快照中獲取最大ID

我想是這樣的：

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'; 

但我得到這個錯誤：

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

有沒有辦法解決這個問題的方法嗎？

Answer 1

問題是，你有兩個查詢CTE後的。只有一個。 CTE連接到查詢。所以，只需添加另一個CTE。事情是這樣的：

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';