我们可以在单个SQL中使用多个"WITH AS" - Oracle SQL

Question

我有一个非常简单的问题:oracle是否允许在单个sql语句中使用多个"WITH AS".

例:

WITH abc AS( select ......)

WITH XYZ AS(select ....) /*This one uses "abc" multiple times*/

Select ....   /*using XYZ multiple times*/

我可以通过多次重复相同的查询来使查询工作,但不想这样做,并利用"WITH AS".这似乎是一个简单的要求,但oracle不允许我:

ORA-00928:缺少SELECT关键字

Answer 1

你可以这样做:

WITH abc AS( select
             FROM ...)
, XYZ AS(select
         From abc ....) /*This one uses "abc" multiple times*/
  Select 
  From XYZ....   /*using abc, XYZ multiple times*/

Answer 2

正确的语法是 -

with t1
as
(select * from tab1
where conditions...
),
t2
as
(select * from tab2
where conditions...
(you can access columns of t1 here as well)
)
select * from t1, t2
where t1.col1=t2.col2;

Answer 3

是的你可以...

WITH SET1 AS (SELECT SYSDATE FROM DUAL), -- SET1 initialised
     SET2 AS (SELECT * FROM SET1)        -- SET1 accessed
SELECT * FROM SET2;                      -- SET2 projected

10/29/2013 10:43:26 AM

按照在公用表表达式中初始化它的顺序