def check_permission(self, permtype, permlabel=None):
		if not self.has_permission(permtype):
			self.raise_no_permission_to(permlabel or permtype)
Returns the table alias (the name might be ambiguous, the alias will
dataset/ETHPy150Open frappe/frappe/frappe/model/document.py/Document.check_permission--crossover with--dataset/ETHPy150Open cloudera/hue/desktop/core/ext-py/Django-1.6.10/django/db/models/sql/compiler.py/SQLCompiler.find_ordering_name