UTEP Oracle 9i
UTEP Oracle 10g Notes

Intersection

Understanding the concept:

The intersection operator returns the records that two recordsets have in common. It is, in essence, a "find the duplicates" operation, and that's the way it's most often used. An intersection is implemented using outer joins.

For example, suppose that you have inherited client lists from several legacy systems

Those legacy tables often have duplicate data.

When using outer join combined with the "IS NOT NULL" operator performs an intersection.