就当删除商品的类别的同时,怎么删除该类别的商品的全部信息呢?
$del="delete * from categories where categories_id=1";
$delpro="delete * from product where categories_id=";
$query1=mysql_query($del);
$query2=mysql_query($delpro);
我这样做怎么不行呢?
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请教大家关于级联删除的问题?
就当删除商品的类别的同时,怎么删除该类别的商品的全部信息呢? $del="delete * from categories where categories_id=1"; $delpro="delete * from product where categories_id="; $query1=mysql_query($del); $query2=mysql_query($delpro); 我这样做怎么不行呢?
$del="delete * from categories where categories_id=1";
$delpro="delete * from product where categories_id=1";
$query1=mysql_query($del);
$query2=mysql_query($delpro);
你也太马虎了吧
--DELETE 级联删除,先删除,再删除所有级联的记录,采用递归触发器,当然要求数据库支持递归触发器功能开启(数据库属性设置中开启他),不过SqlServer只支持32级的递归啊
IF EXISTS (SELECT NAME FROM SYSOBJECTS
WHERE NAME = 'DEL_DOCUMENTTYPE_001' AND TYPE = 'TR')
DROP TRIGGER DEL_DOCUMENTTYPE_001
GO
CREATE TRIGGER DEL_DOCUMENTTYPE_001
ON dbo.DOCUMENTTYPE
FOR DELETE
AS
IF (SELECT COUNT(*) FROM DELETED) > 0
DELETE FROM dbo.DOCUMENTTYPE WHERE UPNO IN (SELECT NO FROM DELETED)
GO
--INSERT 数据插入,验证外键关联逻辑,错误抛出出错信息
IF EXISTS (SELECT NAME FROM SYSOBJECTS
WHERE NAME = 'INS_DOCUMENTTYPE_001' AND TYPE = 'TR')
DROP TRIGGER INS_DOCUMENTTYPE_001
GO
CREATE TRIGGER INS_DOCUMENTTYPE_001
ON dbo.DOCUMENTTYPE
FOR INSERT
AS
IF (SELECT COUNT(*) FROM INSERTED WHERE UPNO IS NOT NULL
AND (UPNO = NO OR UPNO NOT IN (SELECT NO FROM dbo.DOCUMENTTYPE))) > 0
BEGIN
DELETE FROM dbo.DOCUMENTTYPE WHERE NO IN (SELECT NO FROM INSERTED)
RAISERROR('在被引用表 dbo.DOCUMENTTYPE 中没有与外键 UPNO 的引用列的列表匹配的主键或候选键。',16,1)
END
GO
--UPDATE 数据更新,如果更新了外键,验证外键存在
IF EXISTS (SELECT NAME FROM SYSOBJECTS
WHERE NAME = 'UPD_DOCUMENTTYPE_001' AND TYPE = 'TR')
DROP TRIGGER UPD_DOCUMENTTYPE_001
GO
CREATE TRIGGER UPD_DOCUMENTTYPE_001
ON dbo.DOCUMENTTYPE
FOR UPDATE
AS
IF (SELECT COUNT(*) FROM INSERTED WHERE UPNO IS NOT NULL
AND (UPNO = NO OR UPNO NOT IN (SELECT NO FROM dbo.DOCUMENTTYPE))) > 0
BEGIN
SET IDENTITY_INSERT dbo.DOCUMENTTYPE ON
DELETE FROM dbo.DOCUMENTTYPE WHERE NO IN (SELECT NO FROM INSERTED)
-- INSERT INTO dbo.DOCUMENTTYPE SELECT * FROM INSERTED
SELECT * INTO dbo.DOCUMENTTYPE FROM INSERTED
SET IDENTITY_INSERT dbo.DOCUMENTTYPE OFF
RAISERROR('在被引用表 dbo.DOCUMENTTYPE 中没有与外键 UPNO 的引用列的列表匹配的主键或候选键。',16,1)
END
GO