public void addLibrarian(Librarian l) {
		Connection conn =null;
		PreparedStatement pSt=null;
		
		// If l is null, do nothing
		if (l == null)
			return;
		
		try {			
			conn=DriverManager.getConnection("jdbc:mysql://localhost:3306/librarysystem?user=admin&password=123456");
			
			// Insert tuple into Librarian in which attributes are obtained from Librarian object p
			String insert = "INSERT INTO Librarian(idNumber, name, address) VALUES (?, ?, ?)";
			pSt = conn.prepareStatement(insert);	
			pSt.setInt(1, l.getIdNumber());
			pSt.setString(2, l.getName());
			pSt.setString(3, l.getAddress());
			pSt.executeUpdate();
			
		} catch (SQLException e) {
			e.getMessage();
		} finally {
			try {
				if(conn != null)
					conn.close();
				if(pSt != null)
					pSt.close();
			} catch (Exception e) {
			}
		}
	}