Database Design for Betting Community

php database database-design sqlite schema

Quite a task, but here is my attempt:

Members table stores members data; including PerformanceFactor which is periodically re-calculated based on correctness of one's answers.
Transactions table tracks money deposits and withdrawals for each member. The Type field could be 1=deposit, 2=withdrawal, 3=transfer from winnings.
One contest can have many questions, a question belongs to one contest only.
One member can place many member-bets, a member-bet belongs to one member only.Place UNIQUE constraint on MemberID, ContestID to prevent member placing several bets for a specific contest
One member-bet has several answers, each answer belongs to one member bet only; each answer relates to a question. Place UNIQUE constraint on MemberBetID, QuestionID to prevent member placing several answers for a specific question.
DerivedAnswers table contains answers obtained by "statistical analysis" of member answers for a specific contest. Place UNIQUE constraint on ContestID, QuestionID to prevent repeating an answer for a specific question.

CodeHunter