经典SQL语句大全之技巧

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 [' @tblNam

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 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 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

if (select min(score) from tb_table)>60

break

else

continue

end