Outer Joins
An outer join does not require each record in the two joined tables to have a matching record. The joined table retains each record—even if no other matching record exists. Outer joins subdivide further into left outer joins, right outer joins, and full outer joins, depending on which table's rows are retained (left, right, or both).
(In this case left and right refer to the two sides of the JOIN keyword.)
No implicit join-notation for outer joins exists in standard SQL.
Read more about this topic: Join (SQL)
Famous quotes containing the words outer and/or joins:
“No one knows better than children how much they need the authority that protects, that sets the outer limits of behavior with known and prescribed consequences. As one little boy expressed it to his mother, “You care what I do.””
—Leontine Young (20th century)
“All successful men have agreed in one thing,—they were causationists. They believed that things went not by luck, but by law; that there was not a weak or a cracked link in the chain that joins the first and last of things.”
—Ralph Waldo Emerson (1803–1882)