Main.java Source code

Introduction

Here is the source code for Main.java

Source

import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.ResultSet;
import java.sql.ResultSetMetaData;
import java.sql.Statement;

public class Main {
    private static final String DRIVER = "com.mysql.jdbc.Driver";

    private static final String URL = "jdbc:mysql://localhost/testdb";

    private static final String USERNAME = "root";

    private static final String PASSWORD = "";

    public static void main(String[] args) throws Exception {
        Class.forName(DRIVER);
        Connection connection = DriverManager.getConnection(URL, USERNAME, PASSWORD);

        Statement statement = connection.createStatement();
        ResultSet resultSet = statement.executeQuery("SELECT id, username FROM users");
        ResultSetMetaData metadata = resultSet.getMetaData();
        int nullability = metadata.isNullable(1);

        if (nullability == ResultSetMetaData.columnNullable) {
            System.out.println("Columns ID can have a null value");
        } else if (nullability == ResultSetMetaData.columnNoNulls) {
            System.out.println("Columns ID does not allowed to have a null value");
        } else if (nullability == ResultSetMetaData.columnNullableUnknown) {
            System.out.println("Nullability unknown");
        }
    }
}