Oracle Table Connection method

1. Nested loop coupling (NESTED LOOPS)
2, Hash junction (hash join)
3. Sorting merge joins (merge JOIN)
4, Semi-junction (In/exists)
5. Anti-coupling (not in/not exists)
6. Descartes Junction (MERGE JOIN Cartesian)
7, connecting the outer connection
Left OUTER JOIN
Right outer join
Full OUTER JOIN
8. Index coupling

Left Outer connection:
With the table on the left as the benchmark, the table to the right joins with no return value empty.

Right outer connection:
With the table on the right, the table to the left is empty when no return value is returned.

Full connection:
With 2 tables, all columns are returned, and 2 sides are empty.

Internal connection:
Returns a non-empty column

Such as:

Left Table Right Table
ID1 a ID1 1
Id2 B id2 2
ID3 C ID3 3
Id4 D ID4 4
ID5 e Id6 6

Left outer connection
ID1 a 1
Id2 B 2
ID3 C 3
Id4 D 4
ID5 E

Right outer connection
ID1 a 1
Id2 B 2
ID3 C 3
Id4 D 4
Id6 6

Fully connected
ID1 a 1
Id2 B 2
ID3 C 3
Id4 D 4
ID5 E
Id6 6

Internal connection
ID1 a 1
Id2 B 2
ID3 C 3
Id4 D 4

Oracle Table Connection method