Equality Joins

The most common type of join used in the workplace is based on two (or more) tables having equivalent data stored in a common column. These joins are called equality joins but are also referred to as equijoins, inner joins, or simple joins.

SELECT b.title, b.pubid, p.name
FROM books b, publisher p
WHERE b.pubid = p.pubid
AND (b.cost < 15 OR p.pubid = 1)
ORDER BY title;