insert with condition in mysql

Question

in DB tables i've: Patient Table, PatientBasicInfomation Table, PatientImageFindings Table.. i've multiple Questions depend on this design..( note that i'm beginner in DB ) 1) if i have for each Patient an ID.. so according to DB concepts both PatientBasicInfomation, PatientImageFindings should have this key (ID) as a foreign key?!

2) in the Patient Table i should reference to the PatientBasicInfomation, PatientImageFindings by using their private keys so they will be in Patient Table as a foreign keys?! am i thinking correct...

3) Now my big problem: i want to insert in PatientImageFindings Table a record but under condition ID + Date (where Date is an important Field in PatientImageFindings Table, i don't know if i should put it as a private key or not..), how could i do this insertion statement in my java class..(Insertion under conditions)

Answer 1

What you want to do is add a UNIQUE constraint across multiple columns.

This question provides an answer to do just that:
How do I specify unique constraint for multiple columns in MySQL?

alter table votes add unique index(user, email, address);

Unless you have another reason, you should enforce this at the database level and treat exceptions as they arise after attempted INSERT s.