9th Day of Oracle Learning

I have to work overtime on weekends ... Do a lot of learning, and continue to watch the tutorial tonight, multi-table query

1, Cartesian product: Multi-table should pay attention to

2, outside the connection: Before a record, that is (+) This writing, more strange

3, using: Eliminate Descartes Set

4, Unit, Unitall: occasionally useful to

5, INTERSECT: Have seen colleagues used, do not know what meaning, the original is the intersection

It's not much of a study tonight, though.

9th Day of Oracle Learning