use master
declare @DbName varchar(60)
declare @BackSql varchar(1000)

declare myCursor cursor for
SELECT [name] FROM SYSDATABASES
where [name] not in ('master','model','msdb','tempdb')
order by [name]
open myCursor
fetch next from myCursor into @DbName
while(@@FETCH_STATUS = 0)
begin
if datename(weekday, getdate())='星期日' --每周日覆盖上周日的
begin
select @BackSql='Backup DATABASE ['+@DbName+'] to disk=''C:\DbBackUp\'+@DbName+CONVERT(VARCHAR(10),GETDATE(),120)+'星期日.bak'' with format'
end
else--每天覆盖上一天的
begin
select @BackSql='Backup DATABASE ['+@DbName+'] to disk=''C:\database\alldatabase\'+@DbName+CONVERT(VARCHAR(10),GETDATE(),120)+'.bak'' with format'
end
exec(@BackSql)
fetch next from myCursor into @DbName
end
close myCursor
DEALLOCATE myCursor