public Column(String columnName, String type) {
        this.columnName = columnName;
        if (type.equals("character varying")) { this.type = Type.VARCHAR; return; }
        if (type.equals("number")) { this.type = Type.NUMBER; return; }
        if (type.equals("integer")) { this.type = Type.INTEGER; return; }
        if (type.equals("date")) { this.type = Type.DATE; return; }
        throw new RuntimeException("Unknown type: " + type);
    }