1,如何连接数据库..2,如何设置登陆框..3..如何根据权限设置登陆后的窗体操作..4数据库中插入和读取图片..5,commobox.treeview..DataGrid等控件的应用-1, how to connect to database .. 2, how to set up landing box .. 3 .. how the permissions settings of the form after landing operation .. 4 database to inser