SQL Select only rows where multiple relationships exist

Question

Given a parent table \'parent\'

╔═══════════╦══════════╗
║ PARENT_ID ║   NAME   ║
╠═══════════╬══════════╣
║         1 ║ bob      ║
║         2 ║ carol    ║
         


        

Answer 1

name your first table a, and second table b

SELECT parent_id FROM prop b1 
WHERE prop_id=1 and 
EXISTS (SELECT parent_id FROM prop b2 
        WHERE b2.parent_id=b1.parent_id AND b2.prop_id=5)