请问在游标中怎么将数据库更改到指定的数据库

declare @DB Varchar(20)
declare dd_cursor cursor
for select name from [master].[dbo].sysdatabases for read only
open dd_cursor
fetch next from dd_cursor into @DB
while @@fetch_status = 0
begin
print @DB
use @DB --这句有错 是否有别的方法达到同样的效果,更改数据库更改到指定的数据库
end
close dd_cursor
deallocate dd_cursor

[code="sql"]declare @DB Varchar(20)
declare @str varchar(30)
declare dd_cursor cursor
for select name from [master].[dbo].sysdatabases
open dd_cursor
fetch next from dd_cursor into @DB
while @@fetch_status = 0
begin
print @DB
set @str= N'use ' + @DB

exec (@str)
fetch next from dd_cursor into @DB
end
close dd_cursor
deallocate dd_cursor
[/code]