爲什麼我的刪除內部連接不工作？

Question

我想用inner join刪除2個表格。我有一個modifier_category表，這是父表和modifier_items表是孩子。

它們涉及的方法是存儲在所述cat_id列modifier_categories表主ID在modifier_items表

我只可以由item_id查找表modifier_categories匹配的cat_parent_id。

當我運行刪除查詢時，只有modifier_categories表中的行被刪除，但在modifier_items表中沒有被刪除。

以下是我正在使用的查詢。我至少看了好幾百遍，注意到似乎在工作。

任何幫助將非常感激。感謝先進

DELETE mc 
FROM modifier_categories mc 
INNER JOIN modifier_items mi 
ON mi.cat_parent_id=mc.cat_id 
WHERE mc.menu_item_id = 28560 

Answer 1

模式：

drop table if exists people; 
create table people 
( id int primary key, 
    name varchar(100) not null, 
    gender char(1) not null 
); 
insert people (id,name,gender) values 
(1,'Kathy','f'),(2,'John','m'),(3,'Paul','m'),(4,'Kim','m'); 

drop table if exists pets; 
create table pets 
( id int auto_increment primary key, 
    ownerId int not null, 
    name varchar(100) not null, 
    color varchar(100) not null, 
    foreign key `fk_pets_2_people` (ownerId) references people(id) 
); 
insert pets(ownerId,name,color) values 
(1,'Rover','beige'),(2,'Bubbles','purple'),(3,'Spot','black and white'), 
(1,'Rover2','white'); 

查詢：

DELETE p1 
FROM people p1 
JOIN pets p2 
ON p2.ownerId = p1.id 
AND p1.name = 'Paul'; 
-- error 1451: FK violation (you would orphan poor Spot, left to feed himself) 
-- and your constraint said not to do that 


DELETE p2 
FROM people p1 
JOIN pets p2 
ON p2.ownerId = p1.id 
AND p1.name = 'Paul'; 
-- Spot is now gone 

select * from pets; 
+----+---------+---------+--------+ 
| id | ownerId | name | color | 
+----+---------+---------+--------+ 
| 1 |  1 | Rover | beige | 
| 2 |  2 | Bubbles | purple | 
| 4 |  1 | Rover2 | white | 
+----+---------+---------+--------+ 

刷新數據，然後。

DELETE p1,p2 
FROM people p1 
JOIN pets p2 
ON p2.ownerId = p1.id 
AND p1.name = 'Paul'; 

-- 2 rows deleted Spot is now gone 
select * from people; 
+----+-------+--------+ 
| id | name | gender | 
+----+-------+--------+ 
| 1 | Kathy | f  | 
| 2 | John | m  | 
| 4 | Kim | m  | 
+----+-------+--------+ 

select * from pets; 
+----+---------+---------+--------+ 
| id | ownerId | name | color | 
+----+---------+---------+--------+ 
| 1 |  1 | Rover | beige | 
| 2 |  2 | Bubbles | purple | 
| 4 |  1 | Rover2 | white | 
+----+---------+---------+--------+ 

正如問題中的註釋示例中所述，請查看您的特定情況下的級聯刪除（如果相關）。

您的查詢（這是你的意思辦？）

DELETE mi 
FROM modifier_categories mc 
INNER JOIN modifier_items mi 
ON mi.cat_parent_id=mc.cat_id 
WHERE mc.menu_item_id = 28560; 

Answer 2

好了，所以我找到了答案。我想顯式指定兩個表，我想執行刪除。此代碼工作

 $query = "DELETE modifier_categories,modifier_items FROM modifier_categories INNER JOIN modifier_items ON 
modifier_items.cat_parent_id = modifier_categories.cat_id WHERE modifier_categories.menu_item_id = $item_id "; 

Answer 3

爲了從mc表中刪除記錄（出連接結果的）

DELETE mc 
FROM modifier_categories mc 
INNER JOIN modifier_items mi 
ON mi.cat_parent_id=mc.cat_id 
WHERE mc.menu_item_id = 28560 

爲了從mi表中刪除記錄（出來的連接結果）

DELETE mi 
FROM modifier_categories mc 
INNER JOIN modifier_items mi 
ON mi.cat_parent_id=mc.cat_id 
WHERE mc.menu_item_id = 28560 

爲了刪除來自mc和mi表記錄（出連接結果的）可能是你正在尋找這個

DELETE mc,mi 
FROM modifier_categories mc 
INNER JOIN modifier_items mi 
ON mi.cat_parent_id=mc.cat_id 
WHERE mc.menu_item_id = 28560 

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