SQL Server 数据库操作实用技巧锦集

SET NOCOUNT ON
DECLARE @LogicalFileName sysname,
@MaxMinutes INT,
@NewSize INT


USE databasename -- 要操作的数据库名
SELECT @LogicalFileName = 
"databasename_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

declare @max integer,@id integer
declare cur_rows cursor local for select 主字段,count(*) from 表名 group by 主字段 having count(*) > 1
open cur_rows
fetch cur_rows into @id,@max
while @@fetch_status=0
begin
select @max = @max -1
set rowcount @max
delete from 表名 where 主字段 = @id
fetch cur_rows into @id,@max
end
close cur_rows
set rowcount 0

select distinct * from tableName

select distinct * into #Tmp from tableName
drop table tableName
select * into tableName from #Tmp
drop table #Tmp

select identity(int,1,1) as autoID, * into #Tmp from tableName
select min(autoID) as autoID into #Tmp2 from #Tmp group by Name,autoID
select * from #Tmp where autoID in(select autoID from #tmp2)