Equijoin and inner join difference

Question

I am not getting what is the exact difference between equijoin and inner join as both seems same. If any one can help me with an example?

Answer 1

There are four explicit join operators in SQL that have a comparison:

• INNER JOIN
• LEFT JOIN
• RIGHT JOIN
• FULL JOIN

These specify what happens when there are no matching rows. The INNER JOIN specifies that only matches are retained. (There are other types, that go by names such as "semi-joins" and "anti-join", which are implemented using operators such as IN and NOT EXISTS.)

When using these operators, you need to define relations between the two tables. An "equi-join" specifies that all conditions are equality conditions. Equi-joins are mostly important from a performance perspective and because they are so common.

The nature of the comparison and the type of join are orthogonal. That said, the most common type of "join" is an inner equi-join.

Answer 2

• Inner join can have equality (=) and other operators (like <,>,<>) in the join condition.
• Equi join only have equality (=) operator in the join condition.
• Equi join can be an Inner join, Left Outer join, Right Outer join

The USING clause is not supported by SQL Server and Sybase. This clause is supported by Oracle and MySQL.