title: What are Parent-Child relationships?
body: <p>What is the parent and what is the child in a sql relationship?</p>
  
  <p>In my case, I have a part (Say screw), and product material. For argument's sake, a product material (eg steel) can only belong to one part (but not in the real world). So this is 1:n. The part will have its pk as a fk in the ProductMaterial table.</p>
  
  <p>Which is parent and which is child in this case?</p>