private void setReferences(Attribute a1, Attribute a2) {
        System.out.println("Getting references for the attributes");
        try {
            String URL = "jdbc:oracle:thin:@//ondora01.hu.nl:8521/cursus01.hu.nl";
            String USER = "tho6_2014_2b_team3_target";
            String PASSWORD = " tho6_2014_2b_team3_target";
            Connection tempcon = ConnectionFactory.getTargetConnection(URL,USER,PASSWORD);
            String sql = "SELECT UCC1.TABLE_NAME||'.'||UCC1.COLUMN_NAME CONSTRAINT_SOURCE,\n" +
                    "UCC2.TABLE_NAME||'.'||UCC2.COLUMN_NAME REFERENCES_COLUMN\n" +
                    "FROM USER_CONSTRAINTS uc,\n" +
                    "USER_CONS_COLUMNS ucc1,\n" +
                    "USER_CONS_COLUMNS ucc2\n" +
                    "WHERE UC.CONSTRAINT_NAME = UCC1.CONSTRAINT_NAME\n" +
                    "AND UC.R_CONSTRAINT_NAME = UCC2.CONSTRAINT_NAME\n" +
                    "AND UCC1.POSITION = UCC2.POSITION\n" +
                    "AND UC.CONSTRAINT_TYPE = 'R'\n" +
                    "AND (UCC1.TABLE_NAME = '" + a1.getTabel() + "' OR UCC2.TABLE_NAME = '" + a1.getTabel() + "')\n" +
                    "AND (UCC1.TABLE_NAME = '" + a2.getTabel() + "' OR UCC2.TABLE_NAME = '" + a2.getTabel() + "')\n";
            Statement stmt = tempcon.createStatement();
            ResultSet rs = stmt.executeQuery(sql);
            while (rs.next()) {
                String source1 = rs.getString("CONSTRAINT_SOURCE");
                String source2 = rs.getString("REFERENCES_COLUMN");
                System.out.println(source1);
                System.out.println(source2);
                String[] sourceSplit = source1.split("\\.");
                String[] sourceSplit2 = source2.split("\\.");
                if(a1.getTabel().equals(sourceSplit[0])){
                    a1.setReference(sourceSplit[1]);
                    a2.setReference(sourceSplit2[1]);
                } else {
                    a1.setReference(sourceSplit2[1]);
                    a2.setReference(sourceSplit[1]);
                }
                System.out.println("A1 reference: " + a1.getReference());
                System.out.println("A2 reference: " + a2.getReference());
            }
            stmt.close();
        } catch (Exception ex) {
            System.out.println("Het lukt niet om de references op te halen" + ex);
            ex.printStackTrace();
        }
    }