Answer Posted / vasanth

Hi All....!

Natural join is the same as an equi join on (emp.deptno =
dept.deptno).

Natural joins may cause problems if columns are added or
renamed. Also, no more than two tables can be joined using
this method. So, it is best to avoid natural joins as far
as possible.

If you will come to UNION ALL.

UNION ALL query allows you to combine the result sets of 2
or more "select" queries. It returns all rows (even if the
row exists in more than one of the "select" statements.

Each SQL statement within the UNION ALL query must have the
same number of fields in the result sets with similar data
types.

For Example :-

select field1, field2, . field_n
from tables
UNION ALL
select field1, field2, . field_n
from tables;

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