Joins in SQL

Joins in SQL

SQL has both inner joins and outer join

Use where need relation, e.g. "FROM …"

Inner join variations as for relational algebra

Sailors INNER JOIN Reserves ON Sailors.sid = Reserved.sid

Sailors INNER JOIN Reserved USING (sid)

Sailors NATURAL INNER JOIN Reserved

Outer join includes tuples that don’t match

fill in with nulls

3 varieties: left, right, full