Summary of SQL Join Syntax

1. Cross Join
 * the result is Cartesian product or simply product
 * e.g., Movie ''CROSS JOIN'' StarsIn

1. Theta Join
 * Product on some conditions
 * e.g., Movie ''JOIN'' StarsIn ''ON'' title = movieTitle AND year = movieYear

1. Natural Join
 * the condition in theta join is just all pairs of attributes with same name
 * one of each pair of same name is projected out
 * e.g., MovieStar ''NATURAL JOIN'' MovieExec

1. Outer Join
 * augment the result of a join by the dangling tuples, padded with null values
 * e.g., MovieStar ''NATURAL FULL OUTER JOIN'' MovieExec
 1. FULL OUTER JOIN
 1. LEFT OUTER JOIN
 1. RIGHT OUTER JOIN

1. References
 * http://en.wikipedia.org/wiki/Join_(SQL)