What is the main role and purpose of JDBC in working with databases in Java applications?

JDBC (Java Database Connectivity) is a standard API in Java that provides interaction between Java applications and various databases. Its main role is to offer a unified interface for connecting to a database, executing SQL queries, and processing results.

With JDBC, you can:

• Establish a connection to a database via drivers.
• Execute queries (SELECT, INSERT, UPDATE, DELETE).
• Process query results.
• Manage transactions.

Example of simple connection and query using JDBC:

Connection conn = DriverManager.getConnection("jdbc:mysql://localhost:3306/mydb", "user", "password");
Statement stmt = conn.createStatement();
ResultSet rs = stmt.executeQuery("SELECT * FROM users");
while (rs.next()) {
    System.out.println(rs.getString("username"));
}
rs.close();
stmt.close();
conn.close();