This is a a simple SpringBoot project. It is an Implementation of how library works. User can create an account and choose how many books he wants to borrow on a checkout. He can have as many books as he wants and can have as many checkout as he wants.

SpringBoot
PostgreSQL
Maven
Hibernate

+------------+-------------------+---------+
| Field | Type | Notes |
+------------+-------------------+---------+
| Id | Integer (PK) | |
| name | String | |
| surname | String | |
| email | String | |
| age | Integer | |
+------------+-------------------+---------+
|
|
|
|
|
/|\
+----------------+-------------------+---------------------------------+
| Field | Type | Notes |
+----------------+-------------------+---------------------------------+
| Id | Integer (PK) | |
| userId | Integer (FK) | References User(Id) |
| expirationDate | LocalDate | |
| numberOfBooks | Integer | |
| isReturned | Boolean | |
+----------------+-------------------+---------------------------------+
|
|
|
|
|
/|\
+------------------+-------------------+---------------------------------+
| Field | Type | Notes |
+------------------+-------------------+---------------------------------+
| Id | Integer (PK) | |
| checkOutId | Integer (FK) | References CheckOut(Id) |
| isAvailable | Boolean | |
| title | String | |
| author | String | |
| storyDescription | String | |
| publisher | String | |
| publishYear | Integer | |
+------------------+-------------------+---------------------------------+