经典SQL语句大全之技巧

原文地址：http://blog.csdn.net/stone548534/article/details/8081418

1、1=1，1=2的使用，在SQL语句组合时用的较多
“where 1=1”
是表示选择全部 “where 1=2”全部不选，

如：

if@strWhere !=''

begin

set @strSQL = 'select count(*) as Total from [' + @tblName + '] where ' +@strWhere

end

else

begin

set @strSQL = 'select count(*) as Total from [' + @tblName + ']'

end
我们可以直接写成
错误！未找到目录项。

set @strSQL = 'select count(*) as Totalfrom [' + @tblName + '] where 1=1
安定 '+ @strWhere 2、收缩数据库

--重建索引

DBCCREINDEX

DBCC INDEXDEFRAG

--收缩数据和日志

DBCCSHRINKDB

DBCC SHRINKFILE
3、压缩数据库

dbcc shrinkdatabase(dbname)
4、转移数据库给新用户以已存在用户权限

exec sp_change_users_login 'update_one','newname','oldname'

go
5、检查备份集

RESTORE VERIFYONLY fromdisk='E:\dvbbs.bak'
6、修复数据库

ALTER DATABASE [dvbbs] SET SINGLE_USER

GO

DBCC CHECKDB('dvbbs',repair_allow_data_loss) WITH TABLOCK

GO

ALTER DATABASE [dvbbs] SET MULTI_USER

GO
7、日志清除

SET NOCOUNT ON

DECLARE @LogicalFileName sysname,

@MaxMinutes INT,

@NewSize INT

USEtablename -- 要操作的数据库名

SELECT @LogicalFileName = 'tablename_log', -- 日志文件名

@MaxMinutes= 10, -- Limit on time allowed to wrap log.

@NewSize = 1 -- 你想设定的日志文件的大小(M)
Setup / initialize

DECLARE @OriginalSize int

SELECT @OriginalSize = size

FROM sysfiles

WHERE name = @LogicalFileName

SELECT 'Original Size of ' + db_name() + ' LOG is ' +

CONVERT(VARCHAR(30),@OriginalSize) + '8K pages or ' +

CONVERT(VARCHAR(30),(@OriginalSize*8/1024))+ 'MB'

FROM sysfiles

WHERE name = @LogicalFileName

CREATE TABLE DummyTrans

(DummyColumn char (8000) not null)

DECLARE@Counter INT,

@StartTime DATETIME,

@TruncLog VARCHAR(255)

SELECT @StartTime = GETDATE(),

@TruncLog = 'BACKUP LOG ' + db_name() +' WITH TRUNCATE_ONLY'
DBCC SHRINKFILE(@LogicalFileName, @NewSize)

EXEC (@TruncLog)

-- Wrap the log if necessary.

WHILE @MaxMinutes > DATEDIFF (mi, @StartTime, GETDATE()) -- time has notexpired

AND @OriginalSize = (SELECT size FROMsysfiles WHERE name = @LogicalFileName)

AND (@OriginalSize * 8 /1024) >@NewSize

BEGIN -- Outer loop.

SELECT @Counter = 0

WHILE ((@Counter <@OriginalSize / 16) AND (@Counter < 50000))

BEGIN -- update

INSERT DummyTrans VALUES ('Fill Log')DELETE DummyTrans

SELECT @Counter = @Counter + 1

END

EXEC (@TruncLog)

END

SELECT 'Final Size of ' + db_name() + ' LOG is ' +

CONVERT(VARCHAR(30),size) + ' 8K pagesor ' +

CONVERT(VARCHAR(30),(size*8/1024)) +'MB'

FROM sysfiles

WHERE name = @LogicalFileName

DROP TABLE DummyTrans

SET NOCOUNT OFF
8、说明：更改某个表

exec sp_changeobjectowner'tablename','dbo'
9、存储更改全部表
CREATE PROCEDUREdbo.User_ChangeObjectOwnerBatch

@OldOwner as NVARCHAR(128),

@NewOwner as NVARCHAR(128)

AS
DECLARE@Name as NVARCHAR(128)

DECLARE @Owner as NVARCHAR(128)

DECLARE @OwnerName as NVARCHAR(128)
DECLARE curObjectCURSOR FOR

select 'Name' = name,

'Owner' = user_name(uid)

from sysobjects

where user_name(uid)=@OldOwner

order by name
OPEN curObject

FETCH NEXT FROM curObject INTO @Name, @Owner

WHILE(@@FETCH_STATUS=0)

BEGIN

if @Owner=@OldOwner

begin

set @OwnerName = @OldOwner + '.' + rtrim(@Name)

exec sp_changeobjectowner @OwnerName, @NewOwner

end

-- select @name,@NewOwner,@OldOwner
FETCH NEXT FROMcurObject INTO @Name, @Owner

END
close curObject

deallocate curObject

GO

10、SQL SERVER中直接循环写入数据

declare @i int

set @i=1

while @i<30

begin

insert into test (userid) values(@i)

set @i=@i+1

end

案例：

有如下表，要求就裱中所有沒有及格的成績，在每次增長0.1的基礎上，使他們剛好及格:
Name score
Zhangshan
80
Lishi 59
Wangwu
50
Songquan
69
while((selectmin(score)from tb_table)<60)
begin
updatetb_table set score
=score*1.01
wherescore<60
if (select
min(score) from tb_table)>60
break
else
continue
end