SQL Server数据库日志收缩的SQL语句

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

USE r3db -- 要操作的数据库名
Select @LogicalFileName = 'a_Log', -- 日志文件名
@MaxMinutes = 10, -- Limit on time allowed to wrap log.
@NewSize = 10 -- 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