淺析SQL SERVER一個(gè)沒(méi)有公開(kāi)的存儲過(guò)程
從SQLSERVER6.5開(kāi)始,MS提供了一個(gè)非常有用的系統存儲過(guò)程sp_MSforeachtable和sp_MSforeachDB;作為DBA會(huì )經(jīng)常需要檢查所有的數據庫或用戶(hù)表,比如:檢查所有數據庫的容量;看看指定數據庫所有用戶(hù)表的容量,所有表的記錄數...,我們一般處理這樣的問(wèn)題都是用游標分別處理處理,比如:在數據庫檢索效率非常慢時(shí),我們想檢查數據庫所有的用戶(hù)表,我們就必須這樣寫(xiě)游標:
DECLARE @TableName varchar(255)
DECLARE @ExeSQL varchar(4000)
DECLARE Table_Cursor CURSOR FOR SELECT [name] FROM sysobjects WHERE xtype=‘U‘
OPEN Table_Cursor
FETCH NEXT FROM Table_Cursor INTO @TableName
WHILE(@@FETCH_STATUS=0)
BEGIN
PRINT @TableName
SELECT @ExeSQL=‘DBCC CHECKTABLE(‘‘‘+@TableName+‘‘‘)‘
EXEC(@EXESQL)
FETCH NEXT FROM Table_Cursor INTO @TableName
END
CLOSE Table_Cursor
DEALLOCATE Table_Cursor
GO
如果我們用sp_MSforeachtable就可以非常方便的達到相同的目的:
EXEC sp_MSforeachtable @command1="print ‘?‘ DBCC CHECKTABLE(‘?‘)"
大家可以看出這樣就更加簡(jiǎn)潔(雖然在后臺也是通過(guò)游標來(lái)處理的),下面我們就仔細分析一下sp_MSforeachtable這個(gè)存儲過(guò)程:
我們看看sp_MSforeachtable詳細的CODE:
USE MASTER
GO
SP_HELPTEXT sp_MSforeachtable
--下面時(shí)sp_MSforeachtable的原始代碼
CREATE proc sp_MSforeachtable
@command1 nvarchar(2000), @replacechar nchar(1) = N‘?‘, @command2 nvarchar(2000) = null,
@command3 nvarchar(2000) = null, @whereand nvarchar(2000) = null,
@precommand nvarchar(2000) = null, @postcommand nvarchar(2000) = null
as
/* This proc returns one or more rows for each table (optionally, matching @where), with each table defaulting to its
own result set */
/* @precommand and @postcommand may be used to force a single result set via a temp table. */
/* Preprocessor won‘t replace within quotes so have to use str(). */
declare @mscat nvarchar(12)
select @mscat = ltrim(str(convert(int, 0x0002)))
if (@precommand is not null)
exec(@precommand)
/* Create the select */
exec(N‘declare hCForEach cursor global for select ‘‘[‘‘ + REPLACE(user_name(uid), N‘‘]‘‘, N‘‘]]‘‘) + ‘‘]‘‘ + ‘‘.‘‘ + ‘‘[‘‘
+ REPLACE(object_name(id), N‘‘]‘‘, N‘‘]]‘‘) + ‘‘]‘‘ from dbo.sysobjects o ‘
+ N‘ where OBJECTPROPERTY(o.id, N‘‘IsUserTable‘‘) = 1 ‘ + N‘ and o.category & ‘ + @mscat + N‘ = 0 ‘
+ @whereand)
declare @retval int
select @retval = @@error
if (@retval = 0)
exec @retval = sp_MSforeach_worker @command1, @replacechar, @command2, @command3
if (@retval = 0 and @postcommand is not null)
exec(@postcommand)
return @retval
這個(gè)系統存儲過(guò)程有7個(gè)參數:
@command1 nvarchar(2000), --第一條運行的T-SQL指令
@replacechar nchar(1) = N‘?‘, --指定的占位符號
@command2 nvarchar(2000) = null,--第二條運行的T-SQL指令
@command3 nvarchar(2000) = null, --第三條運行的T-SQL指令
@whereand nvarchar(2000) = null, --可選條件來(lái)選擇表
@precommand nvarchar(2000) = null, --在表前執行的指令
@postcommand nvarchar(2000) = null --在表后執行的指令
所以上面的語(yǔ)句也可以這樣寫(xiě):
EXEC sp_MSforeachtable @command1="print ‘?‘",
@command2= "DBCC CHECKTABLE(‘?‘)"
了解參數以后,就讓我們做幾個(gè)實(shí)列吧:
1.獲得每個(gè)表的記錄數和容量:
EXEC sp_MSforeachtable @command1="print ‘?‘",
@command2="sp_spaceused ‘?‘",
@command3= "SELECT count(*) FROM ? "
2.更新PUBS數據庫中已t開(kāi)頭的所有表的統計:
EXEC sp_MSforeachtable @whereand="and name like ‘t%‘",
@replacechar=‘*‘,
@precommand="print ‘Updating Statistics.....‘ print ‘‘",
@command1="print ‘*‘ update statistics * ",
@postcommand= "print‘‘print ‘Complete Update Statistics!‘"
sp_MSforeachDB除了@whereand外,和sp_MSforeachtable的參數是一樣的,我們可以通過(guò)這個(gè)存儲過(guò)程檢測所有的數據庫,比如:
1.檢查所有的數據庫
EXEC sp_MSforeachdb @command1="print ‘?‘",
@command2="DBCC CHECKDB (?) "
有了上面的分析,我們可以建立自己的sp_MSforeachObject:
USE MASTER
GO
CREATE proc sp_MSforeachObject
@objectType int=1,
@command1 nvarchar(2000),
@replacechar nchar(1) = N‘?‘,
@command2 nvarchar(2000) = null,
@command3 nvarchar(2000) = null,
@whereand nvarchar(2000) = null,
@precommand nvarchar(2000) = null,
@postcommand nvarchar(2000) = null
as
/* This proc returns one or more rows for each table (optionally, matching @where), with each table defaulting to its
own result set */
/* @precommand and @postcommand may be used to force a single result set via a temp table. */
/* Preprocessor won‘t replace within quotes so have to use str(). */
declare @mscat nvarchar(12)
select @mscat = ltrim(str(convert(int, 0x0002)))
if (@precommand is not null)
exec(@precommand)
/* Defined @isobject for save object type */
Declare @isobject varchar(256)
select @isobject= case @objectType when 1 then ‘IsUserTable‘
when 2 then ‘IsView‘
when 3 then ‘IsTrigger‘
when 4 then ‘IsProcedure‘
when 5 then ‘IsDefault‘
when 6 then ‘IsForeignKey‘
when 7 then ‘IsScalarFunction‘
when 8 then ‘IsInlineFunction‘
when 9 then ‘IsPrimaryKey‘
when 10 then ‘IsExtendedProc‘
when 11 then ‘IsReplProc‘
when 12 then ‘IsRule‘
end
/* Create the select */
/* Use @isobject variable isstead of IsUserTable string */
EXEC(N‘declare hCForEach cursor global for select ‘‘[‘‘ + REPLACE(user_name(uid), N‘‘]‘‘, N‘‘]]‘‘) + ‘‘]‘‘ + ‘‘.‘‘ + ‘‘[‘‘ +
REPLACE(object_name(id), N‘‘]‘‘, N‘‘]]‘‘) + ‘‘]‘‘ from dbo.sysobjects o ‘
+ N‘ where OBJECTPROPERTY(o.id, N‘‘‘+@isobject+‘‘‘) = 1 ‘+N‘ and o.category & ‘ + @mscat + N‘ = 0 ‘
+ @whereand)
declare @retval int
select @retval = @@error
if (@retval = 0)
exec @retval = sp_MSforeach_worker @command1, @replacechar, @command2, @command3
if (@retval = 0 and @postcommand is not null)
exec(@postcommand)
return @retval
GO
這樣我們來(lái)測試一下:
1.獲得所有的存儲過(guò)程的腳本:
EXEc sp_MSforeachObject @command1="sp_helptext ‘?‘ ",@objectType=4
2.獲得所有的視圖的腳本:
EXEc sp_MSforeachObject @command1="sp_helptext ‘?‘ ",@objectType=2
3.比如在開(kāi)發(fā)過(guò)程中,沒(méi)一個(gè)用戶(hù)都是自己的OBJECT OWNER,所以在真實(shí)的數據庫時(shí)都要改為DBO:
EXEc sp_MSforeachObject @command1="sp_changeobjectowner ‘?‘, ‘dbo‘",@objectType=1
EXEc sp_MSforeachObject @command1="sp_changeobjectowner ‘?‘, ‘dbo‘",@objectType=2
EXEc sp_MSforeachObject @command1="sp_changeobjectowner ‘?‘, ‘dbo‘",@objectType=3
EXEc sp_MSforeachObject @command1="sp_changeobjectowner ‘?‘, ‘dbo‘",@objectType=4
這樣就非常方便的將每一個(gè)數據庫對象改為DBO.
當然還要很多非常好的功能,大家可以自己深入研究吧:-)
