4
查詢下面返回NULL如果menu_items.parent
不是這是錯誤的。IF和CASE語句在SELECT查詢中帶有子查詢
我想在這裏做的是,如果menu_items.parent
行的值是0 然後返回它的原始值,但如果該值不爲0 然後返回的相應行的名稱(VARCHAR)什麼是價值。
任何想法爲什麼我總是得到NULL?
注意:所有其他選定的列都是正常的,因此查詢本身很好。
由於
實施例1:
SELECT
...
...
(
CASE
WHEN menu_items.parent = '0' THEN menu_items.parent
ELSE (SELECT name FROM menu_items WHERE id = menu_items.parent)
END
) AS ParentID
...
...
FROM menus
INNER JOIN menu_items ...
...
...
實施例2:
SELECT
...
...
IF
(
menu_items.parent = '0',
menu_items.parent,
(SELECT name FROM menu_items WHERE id = menu_items.parent)
) ParentID
...
...
FROM menus
INNER JOIN menu_items ...
...
...
實際查詢:
SELECT
menus.name AS MenuName,
menu_items.id AS MenuItemsId,
menu_items.name AS MenuItemsName
/*
Sub section should go here
*/
FROM users
INNER JOIN assigned_menus ON assigned_menus.fk_users_id = users.id
INNER JOIN menu_items ON menu_items.id = assigned_menus.fk_menu_items_id
INNER JOIN menus ON menus.id = menu_items.fk_menus_id
WHERE
users.id = ? AND
users.is_active = 'YES' AND
menu_items.is_active = 'YES' AND
menus.is_active = 'YES'
ORDER BY
MenuName,
MenuItemsName
menu_items表
ID name parent fk_menu_items_id
1 Menus 0 1
2 Roles 0 1
3 Permissions 0 1
4 Users 0 1
5 Files 0 1
6 File Uploads 0 1
7 University 6 1
8 Details 6 1
9 Progress 6 1
10 Assg 6 1
11 Applications 0 2
12 New 11 2
13 Edit 11 2
14 Rejected 11 2
15 Approved 11 2
16 Exs 0 2
17 Assm 16 2
18 Stf 0 3
19 Std 0 3
20 Prg 19 3
21 Comm 0 4
22 Sms 21 4
23 Sms2 21 4
24 New2 0 4
25 Act 0 4
'menu_items.name'不同,如果'menu_items.parent'不是'0'所以你只返回同一行,而不是數量 – BentCoder 2013-03-07 12:17:21
的名稱現在檢查更新的答案。 – 2013-03-07 12:21:20
爆炸:)非常感謝。 – BentCoder 2013-03-07 12:27:39