How to Enforce Referential Integrity using Foreign Keys in JDBC?
Last Updated :
26 Apr, 2024
Enforcing referential integrity is the fundamental aspect of maintaining data consistency and integrity in a relational database. Referential integrity ensured that the relationships between the tables remained valid, preventing orphaned or inconsistent data. The use of the foreign key is one of the mechanisms for enforcing referential integrity in a database management system (DBMS). In Java Database Connectivity (JDBC), java API is used for interacting with the databases, enforcing the referential integrity using the foreign keys involved the defining and managing these constraints programmatically in your application.
Prerequisites
The following are prerequisites to enforce referential integrity using foreign keys in JDBC:
- Knowledge of Relational Databases
- Knowledge of Java Programming
- Understanding the fundamentals of JDBC (Java Database Connectivity)
- Database Management System
- Integrated Development Environment (IDE)
Note: If you met above prerequisites, you can easily enforce referential integrity using foreign keys in JDBC .
Enforce Referential Integrity using Foreign Keys in JDBC
Step 1: Create Database Schema
Create two tables in your database, and name it as "Customers" and "Orders".
The below figure shows the tables of Customers and Orders.
The above tables doesn't contain any rows.
Step 2: Set Up Eclipse Project
- Open Eclipse and create one new Java Project.
- Add JDBC driver library into your Java project's build path. If you are using the MySQL, make sure you would add the MySQL JDBC driver jar file.
Here is the path for JDBC driver library that means MySQL JDBC driver jar file.
Step 3: Create Java Classes and implement the code
Create a Customer.java class file in src folder in your Java project, write below code in it.
Java
public class Customer {
private int id;
private String name;
public int getId() {
return id;
}
public void setId(int id) {
this.id = id;
}
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
public Customer(int id, String name) {
super();
this.id = id;
this.name = name;
}
public Customer()
{
}
}
Create a Order.java class file in src folder in your Java project, write below code in it.
Java
public class Order {
private int id;
private int customerId;
public int getId() {
return id;
}
public void setId(int id) {
this.id = id;
}
public int getCustomerId() {
return customerId;
}
public void setCustomerId(int customerId) {
this.customerId = customerId;
}
public Order(int id, int customerId) {
super();
this.id = id;
this.customerId = customerId;
}
public Order()
{
}
}
Create a DatabaseConnector.java class file in src folder in your Java project, write below code in it.
Java
import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.SQLException;
public class DatabaseConnector {
private static final String URL = "jdbc:mysql://localhost:3307/work";
private static final String USERNAME = "root";
private static final String PASSWORD = "tiger";
public static Connection getConnection() throws SQLException {
return DriverManager.getConnection(URL, USERNAME, PASSWORD);
}
}
Note: Make sure that you have to change the database url, username, password according to your database.
Create a CustomerDAO.java class file in src folder in your Java project, write below code in it.
Java
import java.sql.Connection;
import java.sql.PreparedStatement;
import java.sql.SQLException;
public class CustomerDAO {
public void insert(Customer customer) {
String sql = "INSERT INTO Customers (CustomerID, Name) VALUES (?, ?)";
try (Connection conn = DatabaseConnector.getConnection();
PreparedStatement pstmt = conn.prepareStatement(sql)) {
pstmt.setInt(1, customer.getId());
pstmt.setString(2, customer.getName());
pstmt.executeUpdate();
} catch (SQLException e) {
e.printStackTrace();
}
}
}
Create a OrderDAO.java class file in src folder in your Java project, write below code in it.
Java
import java.sql.Connection;
import java.sql.PreparedStatement;
import java.sql.SQLException;
public class OrderDAO {
public void insert(Order order) {
String sql = "INSERT INTO Orders (OrderID, CustomerID) VALUES (?, ?)";
try (Connection conn = DatabaseConnector.getConnection();
PreparedStatement pstmt = conn.prepareStatement(sql)) {
pstmt.setInt(1, order.getId());
pstmt.setInt(2, order.getCustomerId());
pstmt.executeUpdate();
} catch (SQLException e) {
e.printStackTrace();
}
}
}
Create a TestApplication.java class file in src folder in your Java project, write below code in it. This code is used to insert the data into the database.
Java
public class TestApplication {
public static void main(String[] args) {
// Inserting a customer
Customer customer = new Customer();
customer.setId(1);
customer.setName("John Doe");
CustomerDAO customerDAO = new CustomerDAO();
customerDAO.insert(customer);
// Inserting an order for the customer
Order order = new Order();
order.setId(101);
order.setCustomerId(1); // Assuming John Doe has CustomerID 1
OrderDAO orderDAO = new OrderDAO();
orderDAO.insert(order);
System.out.println("Your data is Successfully inserted...");
}
}
Step 4: Run the Application
- Run the above code, right click on the Java project in Project Explore.
- Select Run As > Java Application.
The output will be shown in console window in your Eclipse as shown below:
Step 5: Verification
If you want to check the data is successfully inserted or not. you can check the tables in your database. If the data is present in the table, it is successfully inserted into your table, otherwise it is not inserted into your table.
Example:
The above two tables are inserted the rows successfully.
Similar Reads
How to Handle SQL Injection in JDBC using PreparedStatement? In this article, we can learn how to prevent SQL injection in JDBC by using Java programming. Basically, SQL injection is a type of security vulnerability It occurs when hackers or attackers can change or manipulate the SQL query, and this can lead to unauthorized access to resources and also perfor
4 min read
How to use the JDBC Savepoint Interface for Nested Transactions? The JDBC Savepoint Interface offers the mechanism for establishing the points within the transactions and allowing for partial rollback if needed to the user. Transactions in JDBC are particularly crucial for maintaining data integrity by ensuring that the set of operations either entirely succeeds
4 min read
How to Get the Insert ID in JDBC? In Java, for getting the insert ID in JDBC, we have built-in methods like getGeneratedKeys(). This method can be able to get the inserted ID in JDBC. Here, in this article, we have used PreparedStatement for insertion purposes and the SQL Injection attack free also. After performing an insertion ope
3 min read
How to handle Duplicate Key Violations in JDBC? The JDBC is the Application Programming Interface for Java programming language. In this article, we will learn how to handle duplicate key violations in JDBC by using try and catch block. If we insert new data with an already existing primary key, we get an SQL exception then we need to handle that
5 min read
How to Perform a Cascading Delete Using JDBC? In JDBC, the Cascading Delete Operation is a technique of databases that are used to delete the record parent table. In this article, we will learn How to perform a cascading delete using JDBC. Cascading Delete Using JDBCTo Perform a Cascading Delete using JDBC (Java Database Connectivity), you need
2 min read
How to Eliminate Duplicate Keys in Hashtable in Java? HashTable class is part of the Collection framework in Java where the only major difference it has from HashMap is that it's synchronized. Hash table maps keys to values i.e. it internally uses buckets to store key-value pairs and the corresponding bucket to a key-value pair is determined by the key
4 min read