PostgreSQL中的遞歸查詢。 SELECT *

Question

我有遞歸查詢檢索特定的人

WITH RECURSIVE recursetree(id, parent_id) AS (
    SELECT id, parent_id FROM tree WHERE parent_id = 0 
    UNION 
    SELECT t.id, t.parent_id 
    FROM tree t 
    JOIN recursetree rt ON rt.id = t.parent_id 
) 
SELECT * FROM recursetree; 

正如你所看到的，我指定的列清單要檢索的所有兒童。但我想用SELECT *（我在真正的桌子上有很多列，他們可以在將來改變）。有沒有辦法讓所有列沒有單獨定義每個列？

Answer 1

你並不需要在WITH部分指定列。如果您不說，列名將由UNION中的第一個查詢確定：

WITH RECURSIVE recursetree AS (
    SELECT * FROM tree WHERE parent_id = 0 
    UNION 
    SELECT t.* 
    FROM tree t 
    JOIN recursetree rt ON rt.id = t.parent_id 
) 
SELECT * 
FROM recursetree; 

Answer 2

快速劈飛（與原歸隊）：

WITH RECURSIVE recursetree(id, parent_id) AS (
    SELECT id, parent_id FROM tree WHERE parent_id = 0 
    UNION 
    SELECT t.id, t.parent_id 
    FROM tree t 
    JOIN recursetree rt ON rt.id = t.parent_id 
) 
SELECT * 
FROM tree tr 
WHERE EXISTS (SELECT 1 
    FROM recursetree x 
    WHERE x.id = tr.id 
    );