mySQL | having, group by | explained
`\nselect actor_id, director_id\nfrom ActorDirector \n#return pair of (actor_id, director_id) \ngroup by actor_id, director_id\nhaving count(*) >= 3\n#having: c
```\nselect actor_id, director_id\nfrom ActorDirector \n#return pair of (actor_id, director_id) \ngroup by actor_id, director_id\nhaving count(*) >= 3\n#having: condition \n#count(*) means count all include NULL cases\n;\n``\n
['MySQL']