code: public SQLProperty getPrimaryKey() {
  		for (SQLProperty item : collection) {
  			if (item.isPrimaryKey()) {
  				return item;
  			}
  		}
  
  		// try to get id
  		SQLProperty id = findPropertyByName("id");
  
  		return id;
  	}
docs: True if there is a primary key.
  
  @return true if there is a primary key