sql 使用with構建臨時表

with x as
(
select 1 as id ,'Adam' as name from dual  union all
select 2 as id ,'John' as name from dual
)
select * from x

這樣就構造了一個由兩行組成的臨時表

 

 

如果需要構造臨時表來表示表間關係

with a as (select 1 as id from dual union all select 2 as id from dual) , 
     b as (select 1 as id,'Adam' as name from dual union all select 3 as id,'Tom' as name from dual)
select a.id,b.name from a left join b on a.id=b.id

使用逗號 來表示兩表並列，就可以構造兩個臨時表了。