erDiagram
    STUDY ||--o{ INTERVIEW : includes
    PARTICIPANT ||--o{ INTERVIEW : attends
    STUDY {
        int study_id PK
        string topic
    }
    PARTICIPANT {
        int participant_id PK
        string reference_code
    }
    INTERVIEW {
        int interview_id PK
        int study_id FK
        int participant_id FK
        date interview_date
    }