SQL join basic

In SQL, Join is a powerful and useful operation. It can be used to return data from multiple tables.

There are different types of joins (that I know)

• Inner Join (Default in some DBs): Select only the matched rows from two tables
• Left(Right) Outer Join: select all rows from Left(Right) table and matched rows from the second table
• Cross Join: return all rows from both table. Even there are 'NULL' values in its column

ref: http://en.wikipedia.org/wiki/Join_(SQL)#Natural_join