Why Left and Right Joins if only one of them can serve the same purpose?

I understand that left join is used to display all the records from left table whereas the right join is used to display all the records from right table in a join.
However, if we switch the positions of the join tables and perform left join we can get all the records of the left table.
A left join B -> will give all records from A
A right join B ->will give all records from B
B left join A -> will again give all records from B.
The order in which the data is displayed(ie the field order) can also be maintained in the SELECT clause.
So, Why do we have left and right joins separately in existance, when only one of them can serve the same purpose?

Hi,
I think it's because it is sometime more natural to outer join on left or right.
In your data model (or the query you are writing), there is some kind of hierarchy between tables : I feel more natural to have the table with lowest hierarchical level (the root table) on the left. So I sometimes prefer to right outer join...
This is a very personal feeling, I must admit.
To me what is strange is to have chosen left and right as they refer to a "latin" reading direction => forward join and backward join would be more meaningful for people that read from right to left.
+And I prefer the new joining syntax that doesn't us the {noformat}(+){noformat} sign...+

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Hi,
Why we need two joins while we can do it just by replacing the tables?
Query 1.
SELECT e.ename, d.dname
FROM emp e LEFT JOIN dept d ON e.deptno = d.deptno ;
Query 2.
SELECT e.ename, d.dname
FROM emp e RIGHT JOIN dept d ON e.deptno = d.deptno ;
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Query 3.
SELECT e.ename, d.dname
FROM dept d LEFT JOIN emp e ON e.deptno = d.deptno ;
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Regards,
Danish

Danish wrote:
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Why Left and Right Joins if only one of them can serve the same purpose?

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