private void validateCharacteristics() {
		if (!fieldCharacteristics.isEmpty()) {
			{
				String defaultValue = getDefualt();
				if (fieldCharacteristics.contains(FieldCharacteristics.NOT_NULL) && 
						defaultValue != null &&	defaultValue.equals("NULL")) {
					throw new IllegalStateException("Cannot make field \"NOT NULL\" and " +
							"\"DEFAULT NULL\"");
				}
			}
			if (fieldCharacteristics.contains(FieldCharacteristics.UNIQUE) && 
					fieldCharacteristics.contains(FieldCharacteristics.PRIMARY_KEY)) {
				throw new IllegalStateException("Redundent to define field as " +
						"\"UNIQUE \" and \"DEFAULT NULL\"");
			}
			if (fieldCharacteristics.contains(FieldCharacteristics.PRIMARY_KEY) && 
					!fieldCharacteristics.contains(FieldCharacteristics.NOT_NULL)) {
				throw new IllegalStateException("PRIMARY KEY cannot be NULL. Please " +
						"add \"NOT NULL\" to this field. (" + name + ")");
			}
		}
	}