本存儲過程實現(xiàn)了多級分類檔案 級聯(lián)刪除技術

本存儲過程的特點是 :

n ????????? 可以在不同的數(shù)據(jù)庫表上應用此存儲過程 , 以 達到通用化

n ????????? 同時用戶也可以根據(jù)不同的表結構 , 選擇相應版本的的存儲過程 , 在這里共有三個版本可供用戶選擇 , 分別對應表結構中有無節(jié)點的深度字段等情況

進行調(diào)用本存儲過程時只需要傳遞節(jié)點號及表名即可 , 但是用戶選擇相應版本進行應用時 , 需要針對實際情況作出選擇

版本一

CREATE procedure prcDelete(@vSourceID varchar(30),@Table varchar(20), @iOK int output)

as

declare @iDepth int

declare @SQLString nvarchar(500)

set @SQLString=N'select vID from '+@Table +' where vID = '''+ltrim(rtrim(@vSourceID))+''''

exec(@SQLString)

if @@rowcount > 0

begin

?? ?? set @SQLString=N'select @iDepth=iDepth from '+@table+ ' where vID = '''+ltrim(rtrim(@vSourceID))+''''

???????? exec sp_executesql @SQLString,N'@iDepth int output',@iDepth output

???????? select @vSourceID as vID,@iDepth as iDepth into #t

???????? set @SQLString=N'insert #t select vID,iDepth from '+@Table +' where vParentID in (select vID from #t where iDepth=@iDepth-1)'

???????? while @@rowcount > 0

???????? begin

?????????????????? set @iDepth=@iDepth+1

??????? ?? exec sp_executesql @SQLString,N'@iDepth int',@iDepth

???????? end

???????? set @SQLString=N'delete from '+@Table +' where vID in (select vID from #t) '

???????? begin tran

???????? exec sp_executesql @SQLString

???????? if @@error<>0 goto Err

???????? commit

???????? select @iOK=0

???????? return

???????? Err:

???????? ?? rollback

???????? ?? select @iOK=1

end

else

begin

???????? select @iOK=1

end

?

版本二

CREATE procedure prcDelete(@vSourceID varchar(30),@Table varchar(20), @iOK int output)

as

declare @level int

declare @SQLString nvarchar(500)

set @SQLString=N'select vID from '+@Table +' where vID = '''+ltrim(rtrim(@vSourceID))+''''

exec(@SQLString)

if @@rowcount > 0

begin

???????? set @level=0

???????? select @vSourceID as vID,@level as level into #t

???????? set @SQLString=N'insert #t select vID,@level from '+@Table +' where vParentID in (select vID from #t where level=@level-1) '

???????? while @@rowcount > 0

???????? begin

?????????????????? set @level=@level+1

??????? ?? exec sp_executesql @SQLString,N'@level int',@level

???????? end

???????? set @SQLString=N'delete from '+@Table +' where vID in (select vID from #t) '

???????? begin tran

???????? exec sp_executesql @SQLString

???????? if @@error<>0 goto Err

???????? commit

???????? select @iOK=0

???????? return

???????? Err:

???????? ? ? rollback

???????? ?? select @iOK=1

end

else

begin

???????? select @iOK=1

end

?

版本三

CREATE procedure prcDelete(@vSourceID varchar(30),@Table varchar(20), @iOK int output)

as

declare @vParentID varchar(30)

declare @SQLString nvarchar(500)

set @SQLString=N'select vID from '+@Table +' where vID = '''+ltrim(rtrim(@vSourceID))+''''

exec(@SQLString)

if @@rowcount > 0

begin

???????? select @vSourceID as vID,@vParentID as vParentID into #t

???????? set @SQLString=N'insert #t select vID,vParentID from '+@Table +' where vParentID in (select vID from #t) and vID not in(select vID from #t)'

???????? while @@rowcount > 0

??????? ?? exec(@SQLString)

???????? set @SQLString=N'delete from '+@Table +' where vID in (select vID from #t) '

???????? begin tran

???????? exec sp_executesql @SQLString

???????? if @@error<>0 goto Err

???????? commit

???????? select @iOK=0

???????? return

???????? Err:

???????? ?? rollback

???????? ?? select @iOK=1

end

else

begin

???????? select @iOK=1

end

?

三種版本的比較

版本一適合以下表結構

create table CustomerClass(

vID??? varchar(30) constraint pkCustomerClass primary key ,

vCustomerClassName varchar(40) NOT NULL,

vRemarks???????? varchar(80) NULL,

vParentIDvarchar(30) NULL,

iDepth?????? Int NOT NULL

)

版本二和版本三適合以下表結構

create table CustomerClass(

vID??? varchar(30) constraint pkCustomerClass primary key ,

vCustomerClassName varchar(40) NOT NULL,

vRemarks???????? varchar(80) NULL,

vParentIDvarchar(30) NULL

)

另外用戶如果要在 SQL 查詢分析器進行測試時可用如下方法進行測試 ( 注意執(zhí)行時三個語句一起執(zhí)行 ) :

declare @value int

exec prcDelete '002','CustomerClass',@iOK=@value output

select @value

?

存儲過程說明

n????????? 本存儲過程利用輸出參數(shù)來說明級聯(lián)刪除操作是否成功 , 返回 0 表示成功 ,1 表示失敗

n????????? 本存儲過程利用事務來進行刪除 , 確保操作安全和數(shù)據(jù)的完整性 , 數(shù)據(jù)完整性在這里指的是 , 若某一檔案已經(jīng)在外部引用過了 , 即其他表中的外關鍵字使用過了 , 則刪除本結點或是包含這一結點的結點 , 都會進行事務控制 , 返回 1, 說明不允許刪除

n????????? 另外本存儲過程對傳入的結點進行審核 , 確定在本表中有這一結點時才進行接下來的刪除操作 , 否則返回 1, 說明結點不存在或傳入結點有誤

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