問題與PostgreSQL的

Question

此查詢遞歸CTE產生從1號至4

with recursive z(q) as (
    select 1 
    union all 
    select q + 1 from z where q < 4 
) 
select * from z; 

但是，如果我把它修改這個，

with x as (
    select 1 y 
), 
recursive z(q) as (
    select y from x 
    union all 
    select q + 1 from z where q < 4 
) 
select * from z; 

它給

ERROR: syntax error at or near "z"

我在這裏做錯了什麼？

Answer 1

我想這是因爲RECURSIVE is modifier of WITH statement，不是一個普通的表表達式z的財產，所以你可以使用它像這樣：

with recursive 
x as (
    select 1 y 
), 
z(q) as (
    select y from x 
    union all 
    select q + 1 from z where q < 4 
) 
select * from z; 

sql fiddle demo