@Override
	public boolean equals(Object obj) {
		if (this == obj)
			return true;
		if (obj == null)
			return false;
		if (getClass() != obj.getClass())
			return false;
		QueryAttribute other = (QueryAttribute) obj;
		if (columnName == null) {
			if (other.columnName != null)
				return false;
		} else if (!columnName.equals(other.columnName))
			return false;
		if (tableName == null) {
			if (other.tableName != null)
				return false;
		} else if (!tableName.equals(other.tableName))
			return false;
		return true;
	}