求各位大神，帮帮忙！怎么修改？

你的code好多问题啊。 帮你改了下，没你的环境测试。
create procedure sp_delete_gradute
@end_date datetime,
@min_credit int
AS
declare @sno char(10)
declare cur_row_cursor cursor for
select sno from student where startdate=@end_date
open cur_row_cursor
fetch next from cur_row_cursor into @sno
while @@FETCH_STATUS=0
begin
delete reports where sno=@sno
delete students where sno=@sno
fetch next from cur_row_cursor into @sno
end
close cur_row_cursor
deallocal cur_row_cursor
关于游标有什么不会的话，参考下官方文档哦。
https://msdn.microsoft.com/en-us/library/ms180169.aspx

呵呵，谢谢哒