数据库清除日志文件(LDF文件过大)

清除日志：

declare @logicalfilename sysname,
@maxminutes int,
@newsize int
use szwzcheck -- 要操作的数据库名
select @logicalfilename = 'szwzcheck_log', -- 日志文件名
@maxminutes = 10, -- limit on time allowed to wrap log.
@newsize = 20 -- 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
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

把szwzcheck换成你数据库的名字即可，在查询分析器里面运行。
有全角的空格(为了显示好看),你自己把他换一下.

编辑注：
一般情况下，用下面的语句更简单

dump transaction [jb51] with no_log
backup log [jb51] with no_log
dbcc shrinkdatabase([jb51])

其中jb51就是你要处理的数据库名。