发布时间：2019-09-10 09:29:00
c语言 vs，谢谢
问题描述：
某个基础信息表，与系统中30多个表存在外键关系，当删除基础数据时，需要判断是否已经被用过，如果用过则更改标志位，如果没有用过则直接删除，如何能很好实现这个处理？最好能够自动适应表的变化
问题解决（SQL Server 2005）
-- SQL Server 2005的错误处理容易控制, 因此，SQL Server 2005中可以直接删除, 通过错误处理来确定是否需要更新.
-- 示例如下.
USE tempdb
GO
CREATE TABLE m(
id int PRIMARY KEY,
bz bit)
INSERT m SELECT 1, 0
UNION ALL SELECT 2, 0
CREATE TABLE c(
id int primary key,
a_id int references m(id)
ON DELETE NO ACTION)
INSERT c SELECT 1, 1
GO
-- 删除处理存储过程
CREATE PROC dbo.p_delete
@id int
AS
SET NOCOUNT ON
BEGIN TRY
BEGIN TRAN
DELETE FROM m WHERE id = @id
COMMIT TRAN
END TRY
BEGIN CATCH
ROLLBACK TRAN
IF ERROR_NUMBER() = 547 -- 如果是外键约束错误
BEGIN
BEGIN TRY
BEGIN TRAN -- 更新标志
UPDATE m SET bz = 1
WHERE id = @id
COMMIT TRAN
END TRY
BEGIN CATCH
SELECT ERROR_NUMBER(), ERROR_MESSAGE()
END CATCH
END
ELSE
SELECT ERROR_NUMBER(), ERROR_MESSAGE()
END CATCH
GO
-- 调用
EXEC dbo.p_delete 1
EXEC dbo.p_delete 2
SELECT * FROM m
SELECT * FROM c
GO
DROP TABLE c, m
DROP PROC dbo.p_delete
问题解决（SQL Server 2000）
-- SQL Server 2000 对错误处理不好控制, 一般还是建议做判断
-- 通过系统表查询系统表，可以获取某个表关联的所有外键表
-- 示例存储过程
CREATE PROC dbo.p_Delete
@tbname sysname, -- 基础数据表名
@PkFieldName sysname, -- 基础数据表关键字段名
@PkValue int -- 要删除的基础数据表关键字值
AS
SET NOCOUNT ON
DECLARE @bz bit, @s nvarchar(4000)
DECLARE tb CURSOR LOCAL
FOR
SELECT N
SET @bz = CASE WHEN EXISTS(
SELECT * FROM + QUOTENAME(@tbname)
+ N A, + QUOTENAME(OBJECT_NAME(B.fkeyid))
+ N B
WHERE A. + QUOTENAME((SELECT name FROM syscolumns WHERE colid = B.rkey AND id = B.rkeyid))
+ N = B. + QUOTENAME((SELECT name FROM syscolumns WHERE colid = B.fkey AND id = B.fkeyid))
+ N AND A. + QUOTENAME((SELECT name FROM syscolumns WHERE colid = B.rkey AND id = B.rkeyid))
+ N = @id) THEN 1 ELSE 0 END
FROM sysobjects A
JOIN sysforeignkeys B
ON A.id= B.constid
JOIN sysobjects C
ON A.parent_obj = C.id
WHERE A.xtype = f
AND C.xtype = U
AND OBJECT_NAME(B.rkeyid) = @tbname
OPEN tb
FETCH tb INTO @s
WHILE @@FETCH_STATUS = 0
BEGIN
EXEC sp_executesql @s, N@tbname sysname, @id int, @bz bit OUT, @tbname, @PkValue, @bz OUT
IF @bz = 1
BEGIN
SET @s = NUPDATE + QUOTENAME(@tbname)
+ N SET bz = 1 WHERE + QUOTENAME(@PkFieldName)
+ N = @id
EXEC sp_executesql @s, N@id int, @PkValue
RETURN
END
FETCH tb INTO @s
END
CLOSE tb
DEALLOCATE tb
SET @s = NDELETE FROM + QUOTENAME(@tbname)
+ N WHERE + QUOTENAME(@PkFieldName)
+ N = @id
EXEC sp_executesql @s, N@id int, @PkValue
GO
注意事项
设置表的主/外键关系的时候，不要设置级联删除（ON DELETE CASCADE）