plan

User Table:
UserID(pk)

Survey Table:
SurveyID(pk)

Question Table:
QuestionID(pk)
SurveyID(fk)

Answer Table:
AnswerID(pk)
QuestionID(fk)
Mark

Result Table:
AnswerID(pk)
UserID(pk)

Role Table:
RoleID

UserRole Table:
RoleID(pk)
UserID(pk)

requirements:
1.send surveys to people who answered certain surveys
2.finish a question's sub-questions based on the choice
3.send questions to people who answered certain questions
4.send questions to people who answered certain answers
5.send questions to people who belongs to certain group
6.send questions to people who got certain marks for a certain survey