SQLJoin

Summary of SQL Join Syntax

1. Cross Join

   • the result is Cartesian product or simply product

   • e.g., Movie CROSS JOIN StarsIn

2. Theta Join

   • Product on some conditions

   • e.g., Movie JOIN StarsIn ON title = movieTitle AND year = movieYear

   • default is LEFT INNER JOIN

3. 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

4. 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

   2. LEFT OUTER JOIN

   3. RIGHT OUTER JOIN

5. Semi Join

   • Speeding Up Queries with Semi-Joins and Anti-Joins

   • Speeding Up Queries with Semi-Joins and Anti-Joins

6. References

   • http://en.wikipedia.org/wiki/Join_(SQL)