Pulling data from a PostgreSQL table?

Question

PostgreSQL

you need to display data from the database into an HTML table, options with servlets and jsp are suitable.
Here is the db connection class

import java.sql.*;

public class JDBCExample {

    public static void main(String args[]) {
        Connection c = null;
        Statement stmt = null;
        try {
            Class.forName("org.postgresql.Driver");
            c = DriverManager.getConnection("jdbc:postgresql://localhost:5432/postgres", "postgres", "borntorun");
            stmt = c.createStatement();
            
            String sql = "CREATE TABLE PHONEBOOK "
                    + "(ID INT PRIMARY KEY   NOT NULL,"
                    + " first_name           VARCHAR(20)  NOT NULL, "
                    + " last_name            VARCHAR(20)  NOT NULL, "
                    + " PHONE                VARCHAR(20), "
                    + " EMAIL                VARCHAR(50))";

            stmt.executeUpdate(sql);
            sql = "INSERT INTO PHONEBOOK "
                    + "VALUES (1, 'asf', 'asf', '123', '[email protected]')";
            stmt.executeUpdate(sql);
            sql = "INSERT INTO PHONEBOOK "
                    + "VALUES (1, 'asf', 'asf', '123', '[email protected]')";
            stmt.executeUpdate(sql);
            sql = "INSERT INTO PHONEBOOK "
                    + "VALUES (1, 'asf', 'asf', '123', '[email protected]')";
            stmt.executeUpdate(sql);
            sql = "INSERT INTO PHONEBOOK "
                    + "VALUES (1, 'asf', 'asf', '123', '[email protected]')";;
            stmt.executeUpdate(sql);

            sql = "SELECT * FROM PHONEBOOK";
            ResultSet rs = stmt.executeQuery(sql);
            while (rs.next()) {
                //Получаем значения
                int id = rs.getInt("id");
                String email = rs.getString("EMAIL");
                String phone = rs.getString("PHONE");
                String first = rs.getString("first_name");
                String last = rs.getString("last_name");

                //Вывод данных
                System.out.print("ID: " + id);
                System.out.print(", First name: " + first);
                System.out.print(", Last name: " + last);
                System.out.print(", Phone: " + phone);
                System.out.println(", Email: " + email);
            }
            rs.close();
            stmt.close();
            c.close();
        } catch (Exception e) {
            System.err.println(e.getClass().getName() + ": " + e.getMessage());
            System.exit(0);
        }
    }
}

Answer 1

You can do this with postgresql:

psql -d database_name -H -c "SELECT field1, field2, field3 FROM mytable WHERE field4=true;" -o test.html