Question

我正在尝试使用inner join删除2个表。我有一个modifier_category表，它是父表，而modifier_items表是子表。

它们相关的方式是modifier_categories表主ID，存储在cat_id列中与cat_parent_id表中的modifier_items匹配

我只能通过modifier_categories查找item_id表。

当我运行删除查询时，只有modifier_categories表中的行被删除，但modifier_items表中没有任何内容被删除。

以下是我正在使用的查询。我看了它至少一百次，并注意到似乎工作。

任何帮助都会非常感激。感谢先进的

 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

Answer 1

架构：

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');

查询：

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  |
+----+---------+---------+--------+

然后重新加载数据。

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  |
+----+---------+---------+--------+

正如问题评论中的示例所述，如果相关，请查看Cascade Deletes以了解您的具体情况。

您的查询（这是您打算做的吗？）

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

好的，我找到了答案。我想要明确指定我想要删除的两个表。此代码有效

{{1}}

Answer 3

从mc表中删除记录（已加入的结果中）

 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

从mi表中删除记录（已加入的结果中）

 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

要删除mc和mi表中的记录（已加入的结果中） 5月你正在寻找这个

 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

请查看类似的post

为什么我的删除内部联接不起作用？

3 个答案: