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

class Sqlite {
	public Connection open() {
		Connection conn = null;
		try {
			conn = tryOpen();
		}catch(SQLException ex) {
			System.err.println("Hiba a megnyitás során!");
		}catch(ClassNotFoundException ex) {
			System.err.println("Hiba a meghajtó betöltése során!");
		}
		return conn;
	}
	public Connection tryOpen() throws SQLException, ClassNotFoundException {
		Class.forName("org.sqlite.JDBC");
		return DriverManager.getConnection("jdbc:sqlite:zoldzrt.sqlite");
	}
	public void update(Connection conn, String sql) {
		try {
			tryUpdate(conn, sql);
		}catch(SQLException ex) {
			System.err.println("Hiba az sql végrehajtása során!");
		}
	}
	public void tryUpdate(Connection conn, String sql) throws SQLException {
		Statement stmt = conn.createStatement();		
		stmt.executeUpdate(sql);
	}
	public ResultSet query(Connection conn, String sql) {
		ResultSet rs = null;
		try {
			rs = tryQuery(conn, sql);
		}catch(SQLException ex) {
			System.err.println("Hiba a lekérdezés során!");
		}
		return rs;
	}	
	public ResultSet tryQuery(Connection conn, String sql) throws SQLException {
		ResultSet rs = null;		
		Statement stmt = conn.createStatement();
		stmt.setQueryTimeout(30);
		rs = stmt.executeQuery(sql);
		return rs;
	}	
	public void close(Connection conn) {
		try {
			tryClose(conn);
		}catch(SQLException ex) {
			System.err.println("Hiba a bezárás során!");
		}
	}
	public void tryClose(Connection conn) throws SQLException {
		conn.close();
	}
}