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经典SQL话语大全:三、技巧

热度:14   发布时间:2016-05-05 14:19:24.0
经典SQL语句大全:三、技巧

11=11=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 Total from [' + @tblName + '] where 1=1
安定 '+ @strWhere 2、收缩数据库
--重建索引
DBCC REINDEX
DBCC INDEXDEFRAG
--
收缩数据和日志
DBCC SHRINKDB
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 from disk='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


USE tablename --
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 not expired
?AND @OriginalSize = (SELECT size FROM sysfiles 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 pages or ' +
?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 PROCEDURE dbo.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 curObject CURSOR FOR
select 'Name'??? = name,
?? 'Owner'??? = user_name(uid)
from sysobjects
where user_name(uid)[email protected]
order by name

OPEN?? curObject
FETCH NEXT FROM curObject INTO @Name, @Owner
WHILE(@@FETCH_STATUS=0)
BEGIN?????
if @[email protected]
begin
?? set @OwnerName = @OldOwner + '.' + rtrim(@Name)
?? exec sp_changeobjectowner @OwnerName, @NewOwner
end
-- select @name,@NewOwner,@OldOwner

FETCH NEXT FROM curObject INTO @Name, @Owner
END

close curObject
deallocate curObject
GO


10SQL 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 @[email protected]+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((select min(score) from tb_table)<60)

begin

update tb_table set score =score*1.01

where score<60

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

? break

?else

??? continue

end

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