CREATE CONSTRAINT ON (user:User) ASSERT user._id IS UNIQUE
CREATE CONSTRAINT ON (item:Item) ASSERT item._id IS UNIQUE
Now make "Alex" like "Beer".
MERGE (alex:Person{_id:'Alex'})
MERGE (beer:Item{_id:'Beer'})
CREATE alex-[:LIKES]->beer
And make "Steve" like "Beer".
MERGE (steve:Person{_id:'Steve'})
MERGE (beer:Item{_id:'Beer'})
CREATE steve-[:LIKES]->beer
Of course "Alex" likes "Hamburgers" as well.
MERGE (alex:Person{_id:'Alex'})
MERGE (burger:Item{_id:'Hamburger'})
CREATE alex-[:LIKES]->burger