Types Of Users On My Forums

Assume I have three types of users.
Type I can only Read Posts.
Type II can Read and Edit. And
Type III can Read, Edit and Delete Posts.

Now to manage this, do I need to make three different users in my DB or should I just use ASP to determine that what permissions should every user have. For example, Type I users will not have the edit and delete button on thier screens and Type II users won't have delete button on their screens and Type three would have all three buttons.

Even if I make different users in my DB (assuming it's necessary for security), so how would I determine that what connection string should I connect a specific user with since we have to give the user name and password on the ADODB connection string?