int user_id PK

varchar username

varchar email

varchar password_hash

timestamp created_at

int paper_id PK

varchar title

varchar author

varchar category

date publication_date

varchar file_path

int uploaded_by

timestamp upload_date

int session_id PK

int user_id

timestamp login_time

timestamp logout_time

varchar session_status

int search_id PK

int user_id

varchar search_title

varchar search_author

varchar search_category

timestamp search_date

int stat_id PK

int user_id

int total_papers_count

int my_papers_count

int recent_papers_count

timestamp last_refresh

int view_id PK

int user_id

int paper_id

timestamp timestamp

varchar view_data

varchar action_type

int download_id PK

int user_id

int paper_id

timestamp timestamp

timestamp download_date

varchar download_path

int category_id PK

varchar category_name

varchar category_description

int recent_id PK

int user_id

int paper_id

timestamp timestamp

timestamp upload_date

int display_order