Simple Search Form

[Knight Of Nih]

I have to make a simple search for
I have to search for documents by either: keyword, author, subject (there can be 3 different search boxes.

The tables I have are

Tbldocuments
Docid (Pk)
Authid
Title
Subid

Tblauthor
Authid(Pk)
Firstname
Lastname

Tblsubjects
Subjects(Pk)


Tbldocsub
Subjects (FK)
Docid (FK)

Thanks
Knight Of Nih