Which organizations are not a parent organization of others? List the organization id.
CREATE TABLE organizations (organization_id VARCHAR, parent_organization_id VARCHAR)
SELECT organization_id FROM organizations EXCEPT SELECT parent_organization_id FROM organizations
### Context: CREATE TABLE organizations (organization_id VARCHAR, parent_organization_id VARCHAR) ### Question: Which organizations are not a parent organization of others? List the organization id. ### Answer: SELECT organization_id FROM organizations EXCEPT SELECT parent_organization_id FROM organizations