IN given sql statement no condition is mentioned....so it displays all possible rows m*n.
- in inner join we generally use a condition like "table1.attributes (operator) table2.attributes" [here operator can be any valid one]
-in equijoin it is similar to innerjoin like above but here operator we use is only equality operator(=) and not any else between the attributes.
-in natural join you no need to mention equality condition also as it is implicitly understood....
so,
JOIN+NO CONDITION = CROSS-JOIN
JOIN+EQUALITY CONDITION = EQUI-JOIN
JOIN+ANY VALID CONDITION = INNER-JOIN