SQL Server实现自动收缩数据库日志文件

--在作业中 执行下面SQL代码 即可实现 自动收缩日志文件。（MSSQL 维护计划中没有提供自动收缩日志文件的功能）
--非 镜像 复制订阅 日志传送的情况下 执行。 如果存在日志传送莫要执行 否则日志传送会失败
declare @exec_sql nvarchar(1200),@simple_sql nvarchar(1200),@full_sql nvarchar(1200)
declare @db_name varchar(128)
declare @db_count int
select @db_count=COUNT(1) from sys.databases where database_id >4
declare @j int
set @j =1

while @j<=@db_count 
begin
        select @db_name=name from (select ROW_NUMBER() over(order by name)rn,name from sys.databases where database_id >4 )as tmp where rn=@j
        SET @simple_sql=N' use [master] ' + Char(10) + Char(13) +'Alter DATABASE ['+@db_name+'] SET RECOVERY SIMPLE WITH NO_WAIT'
        EXEC Sp_executesql  @simple_sql,N'@db_name varchar(128)',@db_name
        
        SET @exec_sql=N'USE ['+@db_name+']'+ Char(10) + Char(13) +'DBCC SHRINKFILE (N'''+@db_name+'_log'' , 0, TRUNCATEONLY)'
        EXEC Sp_executesql  @exec_sql,N'@db_name varchar(128)',@db_name
        
        SET @full_sql =N' use [master] ' + Char(10) + Char(13) +'Alter DATABASE ['+@db_name+'] SET RECOVERY FULL WITH NO_WAIT'
        EXEC Sp_executesql  @full_sql,N'@db_name varchar(128)',@db_name
                
    set @j =@j+1
end