The difference between left join and right join in Oracle talking about _oracle

In layman's terms:

The number of connections for a LEFT join B is the same as the number of records in Table A

A RIGHT join B has the same number of records as the number of records in table B

A LEFT join B equivalence B right join A

Table A:

Field_k, field_a

1 A

3 b

4 C

Table B:

Field_k, Field_b

1 x

2 y

4 Z

Select A.field_k, A.field_a, B.field_k, b.field_b

From a LEFT join B on A.field_k=b.field_k

Field_k field_a Field_k field_b

----------    ----------    ----------    ----------

1 a 1 x

3 b NULL NULL

4 C 4 Z

Select A.field_k, A.field_a, B.field_k, b.field_b

From a RIGHT join B on A.field_k=b.field_k

Field_k field_a Field_k field_b

----------    ----------    ----------    ----------

1 a 1 x

Null null 2 y

4 C 4 Z--

As an example:

Suppose the data in table A and table B are like this.

A b

ID Name ID Stock

1 a 1 15

2 B 2 50

3 C

SELECT * from a INNER join B on a.id=b.id

This syntax is the inner join in the connection query, and it produces the result

Two table-matched records appear in the results list.

According to the table above, the result is this

a.ID name b.ID Stock

1 a 1 15

2 B 2 50

----------------------------

SELECT * FROM A,b where a.id=b.id

This syntax is another form of inner join, and its execution is the same as inner join

--------------------------------

SELECT * from a left/right join B on a.id=b.id

This is the left outer join or the right outer join in the outer join syntax

If it is a left outer join, it will show all records in Table A,

Select a.*,b.* from a LEFT join B on a.id=b.id

The result of the query is this:

a.ID name b.ID Stock

1 a 1 15

2 B 2 50

3 c NULL NULL

--------------------------------------------

If it's a right outer join, it will show all the records in table B,

Select a.*,b.* from right join B on a.id=b.id

The result of the query is this:

a.ID name b.ID Stock

1 a 1 15

2 B 2 50

--

Select a.*,b.* from a LEFT join B on a.k = B.K

Select a.*,b.* from a left outer join B on A.K =B.K

----------the top two. Left join is shorthand for left outer join

Select a.*,b.* from a left inner join B on a.k = B.K

There is no such wording, wrong statement.