在SQL Server 2005中,我可以在不设置表格属性的情况下进行级联删除吗？

Question

我有一个充满客户数据的数据库.这是如此之大,以至于操作起来非常麻烦,我宁愿将其减少到10%的客户,这对于开发来说是充足的.我有很多表,我不想用"ON DELETE CASCADE"改变它们,特别是因为这是一次性的交易.

我可以执行删除操作,在没有先设置它们的情况下级联所有表吗？如果没有,我最好的选择是什么？

Answer 1

结合您的建议和我在网上找到的脚本,我制作了一个程序,可以生成SQL,无论如何都可以运行以执行级联删除ON DELETE CASCADE.这可能是浪费时间,但我写得很开心.这样做的一个好处是,你可以GO在每一行之间放一个语句,它不一定是一个大事务.原来是递归程序; 这个将递归展开到堆栈表中.

create procedure usp_delete_cascade (
    @base_table_name varchar(200), @base_criteria nvarchar(1000)
)
as begin
    -- Adapted from http://www.sqlteam.com/article/performing-a-cascade-delete-in-sql-server-7
    -- Expects the name of a table, and a conditional for selecting rows
    -- within that table that you want deleted.
    -- Produces SQL that, when run, deletes all table rows referencing the ones
    -- you initially selected, cascading into any number of tables,
    -- without the need for "ON DELETE CASCADE".
    -- Does not appear to work with self-referencing tables, but it will
    -- delete everything beneath them.
    -- To make it easy on the server, put a "GO" statement between each line.

    declare @to_delete table (
        id int identity(1, 1) primary key not null,
        criteria nvarchar(1000) not null,
        table_name varchar(200) not null,
        processed bit not null,
        delete_sql varchar(1000)
    )

    insert into @to_delete (criteria, table_name, processed) values (@base_criteria, @base_table_name, 0)

    declare @id int, @criteria nvarchar(1000), @table_name varchar(200)
    while exists(select 1 from @to_delete where processed = 0) begin
        select top 1 @id = id, @criteria = criteria, @table_name = table_name from @to_delete where processed = 0 order by id desc

        insert into @to_delete (criteria, table_name, processed)
            select referencing_column.name + ' in (select [' + referenced_column.name + '] from [' + @table_name +'] where ' + @criteria + ')',
                referencing_table.name,
                0
            from  sys.foreign_key_columns fk
                inner join sys.columns referencing_column on fk.parent_object_id = referencing_column.object_id 
                    and fk.parent_column_id = referencing_column.column_id 
                inner join  sys.columns referenced_column on fk.referenced_object_id = referenced_column.object_id 
                    and fk.referenced_column_id = referenced_column.column_id 
                inner join  sys.objects referencing_table on fk.parent_object_id = referencing_table.object_id 
                inner join  sys.objects referenced_table on fk.referenced_object_id = referenced_table.object_id 
                inner join  sys.objects constraint_object on fk.constraint_object_id = constraint_object.object_id
            where referenced_table.name = @table_name
                and referencing_table.name != referenced_table.name

        update @to_delete set
            processed = 1
        where id = @id
    end

    select 'print ''deleting from ' + table_name + '...''; delete from [' + table_name + '] where ' + criteria from @to_delete order by id desc
end

exec usp_delete_cascade 'root_table_name', 'id = 123'

Answer 2

除非您想要维护Chris提出的所有相关查询,否则ON DELETE CASCADE是迄今为止最快捷,最直接的解决方案.如果你不希望它是永久性的,为什么你没有一些T-SQL代码可以像这里一样打开和关闭这个选项

1. 删除原始Tbl_A_MyFK约束(没有ON DELETE CASCADE)

   ALTER TABLE Tbl_A DROP CONSTRAINT Tbl_A_MyFK

2. Tbl_A_MyFK使用ON DELETE CASCADE 设置约束

   ALTER TABLE Tbl_A ADD CONSTRAINT Tbl_A_MyFK FOREIGN KEY (MyFK) REFERENCES Tbl_B(Column) ON DELETE CASCADE

3. 在这里你可以删除

   DELETE FROM Tbl_A WHERE ...

4. 放弃你的约束 Tbl_A_MyFK

   ALTER TABLE Tbl_A DROP CONSTRAINT Tbl_A_MyFK

5. 在Tbl_A_MyFK没有ON DELETE CASCADE的情况下设置约束

   ALTER TABLE Tbl_A ADD CONSTRAINT Tbl_A_MyFK FOREIGN KEY (MyFK) REFERENCES (Tbl_B)

Answer 3

这是针对人口稀少的数据模型优化的已接受答案的一个版本.它在将数据添加到删除列表之前检查FK链中是否存在数据.我用它来清理测试数据.

不要在活动的事务数据库中使用它 - 它将持有锁太长时间.

/*
-- ============================================================================
-- Purpose: Performs a cascading hard-delete.
--          Not for use on an active transactional database- it holds locks for too long.
--          (http://stackoverflow.com/questions/116968/in-sql-server-2005-can-i-do-a-cascade-delete-without-setting-the-property-on-my)
-- eg:
exec dbo.hp_Common_Delete 'tblConsumer', 'Surname = ''TestDxOverdueOneReviewWm''', 1
-- ============================================================================
*/
create proc [dbo].[hp_Common_Delete]
(
    @TableName sysname, 
    @Where nvarchar(4000),  -- Shouldn't include 'where' keyword, e.g. Surname = 'smith', NOT where Surname = 'smith'
    @IsDebug bit = 0
)
as
set nocount on

begin try
    -- Prepare tables to store deletion criteria.  
    -- #tmp_to_delete stores criteria that is tested for results before being added to #to_delete
    create table #to_delete
    (
        id int identity(1, 1) primary key not null,
        criteria nvarchar(4000) not null,
        table_name sysname not null,
        processed bit not null default(0)
    )
    create table #tmp_to_delete 
    (
        id int primary key identity(1,1), 
        criteria nvarchar(4000) not null, 
        table_name sysname not null
    )

    -- Open a transaction (it'll be a long one- don't use this on production!)
    -- We need a transaction around criteria generation because we only 
    -- retain criteria that has rows in the db, and we don't want that to change under us.
    begin tran
        -- If the top-level table meets the deletion criteria, add it
        declare @Sql nvarchar(4000)
        set @Sql = 'if exists(select top(1) * from ' + @TableName + ' where ' + @Where + ') 
            insert #to_delete (criteria, table_name) values (''' + replace(@Where, '''', '''''') + ''', ''' + @TableName + ''')'
        exec (@Sql)

        -- Loop over deletion table, walking foreign keys to generate delete targets
        declare @id int, @tmp_id int, @criteria nvarchar(4000), @new_criteria nvarchar(4000), @table_name sysname, @new_table_name sysname
        while exists(select 1 from #to_delete where processed = 0) 
        begin
            -- Grab table/criteria to work on
            select  top(1) @id = id, 
                    @criteria = criteria, 
                    @table_name = table_name 
            from    #to_delete 
            where   processed = 0 
            order by id desc

            -- Insert all immediate child tables into a temp table for processing
            insert  #tmp_to_delete
            select  referencing_column.name + ' in (select [' + referenced_column.name + '] from [' + @table_name +'] where ' + @criteria + ')',
                    referencing_table.name
            from  sys.foreign_key_columns fk
                    inner join sys.columns referencing_column on fk.parent_object_id = referencing_column.object_id 
                            and fk.parent_column_id = referencing_column.column_id 
                    inner join  sys.columns referenced_column on fk.referenced_object_id = referenced_column.object_id 
                            and fk.referenced_column_id = referenced_column.column_id 
                    inner join  sys.objects referencing_table on fk.parent_object_id = referencing_table.object_id 
                    inner join  sys.objects referenced_table on fk.referenced_object_id = referenced_table.object_id 
                    inner join  sys.objects constraint_object on fk.constraint_object_id = constraint_object.object_id
            where referenced_table.name = @table_name
                    and referencing_table.name != referenced_table.name

            -- Loop on child table criteria, and insert them into delete table if they have records in the db
            select @tmp_id = max(id) from #tmp_to_delete
            while (@tmp_id >= 1)
            begin
                select @new_criteria = criteria, @new_table_name = table_name from #tmp_to_delete where id = @tmp_id
                set @Sql = 'if exists(select top(1) * from ' + @new_table_name + ' where ' + @new_criteria + ') 
                    insert #to_delete (criteria, table_name) values (''' + replace(@new_criteria, '''', '''''') + ''', ''' + @new_table_name + ''')'
                exec (@Sql)

                set @tmp_id = @tmp_id - 1
            end
            truncate table #tmp_to_delete

            -- Move to next record
            update  #to_delete 
            set     processed = 1
            where   id = @id
        end

        -- We have a list of all tables requiring deletion.  Actually delete now.
        select @id = max(id) from #to_delete 
        while (@id >= 1)
        begin
            select @criteria = criteria, @table_name = table_name from #to_delete where id = @id
            set @Sql = 'delete from [' + @table_name + '] where ' + @criteria
            if (@IsDebug = 1) print @Sql
            exec (@Sql)

            -- Next record
            set @id = @id - 1
        end
    commit
end try

begin catch
    -- Any error results in a rollback of the entire job
    if (@@trancount > 0) rollback

    declare @message nvarchar(2047), @errorProcedure nvarchar(126), @errorMessage nvarchar(2048), @errorNumber int, @errorSeverity int, @errorState int, @errorLine int
    select  @errorProcedure = isnull(error_procedure(), N'hp_Common_Delete'), 
            @errorMessage = isnull(error_message(), N'hp_Common_Delete unable to determine error message'), 
            @errorNumber = error_number(), @errorSeverity = error_severity(), @errorState = error_state(), @errorLine = error_line()

    -- Prepare error information as it would be output in SQL Mgt Studio
    declare @event nvarchar(2047)
    select  @event =    'Msg ' + isnull(cast(@errorNumber as varchar), 'null') + 
                        ', Level ' + isnull(cast(@errorSeverity as varchar), 'null') + 
                        ', State ' + isnull(cast(@errorState as varchar), 'null') + 
                        ', Procedure ' + isnull(@errorProcedure, 'null') + 
                        ', Line ' + isnull(cast(@errorLine as varchar), 'null') + 
                        ': ' + isnull(@errorMessage, '@ErrorMessage null')
    print   @event

    -- Re-raise error to ensure admin/job runners understand there was a failure
    raiserror(@errorMessage, @errorSeverity, @errorState)
end catch

Answer 4

进入SQL Server Management Studio并右键单击该数据库.选择Tasks-> Generate Scripts.单击下一步两次.在"选项"窗口中,选择将其设置为仅生成CREATE语句,并将所有内容设置为False,但外键除外.点击下一步.选择Tables并再次单击Next.单击"全选"按钮,然后单击"下一步",然后单击"完成"并将脚本发送到您选择的查询窗口或文件(不要使用剪贴板,因为它可能是一个很大的脚本).现在删除添加表的所有脚本,您应该留下一个脚本来创建外键.

制作该脚本的副本,因为它是将数据库还原到当前状态的方式.使用搜索和替换将ON DELETE CASCADE添加到每个约束的末尾.这可能会有所不同,具体取决于您当前设置的FK的方式,您可能需要进行一些手动编辑.

重复脚本生成,但这次将其设置为仅生成DROP语句.务必手动删除生成的表格.运行drop,然后运行已编辑的创建,使它们在删除时全部级联.删除,再次运行删除脚本,然后运行您在开始时保存的脚本.

此外 - 首先备份您的数据库!即使它只是一个开发数据库,​​如果脚本的一部分不太正确,它也会让你头疼.

希望这可以帮助!

顺便说一句 - 你应该用你的完整测试数据进行一些测试,如另一张海报所示,但我可以看到为什么你可能不需要那些用于初始开发.只是不要忘记在某些时候将其作为质量保证的一部分.