在PGSQL重用變量查詢

我有一個查詢，我已經簡化了一點：在PGSQL重用變量查詢

WITH users AS (
    SELECT member_id FROM group_members AS gm 
     JOIN groups AS g on gm.group_id = g.id 
     WHERE g.id = 1337 OR g.parents @> ARRAY[1337] 
    ) 
UPDATE access SET revoked = TRUE 
    WHERE user_id IN (SELECT member_id FROM users) 

RETURNING user_id;

這工作，但我必須把值ID（1337）幾次。這在我的抽象例子中並沒有那麼糟糕，但是由於我使用PHP/PDO，我必須多次傳入相同的變量，所以我的複雜的真實世界查詢&真的很難看。

我正在尋找的是一些技巧，一旦申報我的變量，然後再使用它，像：

DECLARE gid = 1337 
WITH users AS (
    SELECT member_id FROM group_members AS gm 
     JOIN groups AS g on gm.group_id = g.id 
     WHERE g.id = gid OR g.parents @> ARRAY[gid] 
    ) 
UPDATE access SET revoked = TRUE 
    WHERE user_id IN (SELECT member_id FROM users) 

RETURNING user_id;

但顯然是行不通的。

有沒有辦法在pgsql查詢中聲明一個變量並重用它？

來源

2014-06-19 MrGlass

with gid as (
    select 1337 as gid 
), users as (
    select member_id 
    from 
     group_members as gm 
     join 
     groups as g on gm.group_id = g.id 
    where 
     g.id = (select gid from gid) or 
     g.parents @> array[(select gid from gid)] 
) 
update access 
set revoked = true 
where user_id in (select member_id from users)

或做

with gid as (
    select 1337 as gid 
), users as (
    select member_id 
    from 
     group_members as gm 
     join 
     groups as g on gm.group_id = g.id 
     cross join 
     gid 
    where g.id = gid or g.parents @> array[gid] 
) 
update access 
set revoked = true 
where user_id in (select member_id from users)

但如果你從PHP傳遞參數，然後我看不出剛剛放置參數持有人的地方該問題的交叉連接，如果查詢是太醜陋的1337

來源

2014-06-19 20:31:22

在PDO中，您只能使用一次參數，所以我必須多次通過1337。我沒有嘗試交叉連接，這可能是一個體面的方法 – MrGlass

不幸的是沒有好的方式。 Clodaldo顯示了在純SQL中真正可行的唯一方法。

另一種方式，以及我通常的做法是將它包裝在一個簡單的SQL函數中。

CREATE OR REPLACE FUNCTION do_whatever(gid integer) RETURNS SETOF integer AS $$ 
WITH users AS (
    SELECT member_id FROM group_members AS gm 
     JOIN groups AS g on gm.group_id = g.id 
     WHERE g.id = $1 OR g.parents @> ARRAY[$1] 
    ) 
UPDATE access SET revoked = TRUE 
    WHERE user_id IN (SELECT member_id FROM users) 
RETURNING user_id; 
$$ LANGUAGE sql; 

SELECT * FROM do_whatever(1337);

不幸的是PostgreSQL沒有TEMPORARY功能，並DO塊不能帶參數或返回的行集。所以這不是理想的，但它的工作原理。

來源

2014-06-20 01:39:34

在PGSQL重用變量查詢

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