Learn SQL join, inner join, and outer join

For example:

Table A have 12 (8 + 4) entries, 8 entries have valid relation with B
Table B have 80 (77 + 3) entries, 77 entries have valid relation with.

Then the return amount of join is:
Cross join: 12*80
Inner join: 77
Full outer join: 77 + 4 + 3
Left Outer Join: 77 + 4
Right outrer join: 77 + 3

Inner joinCode as the following:

Select * From A, B where a. categoryid = B. categoryid;
Equals:
Select * from a inner join B on A. categoryid = B. categoryid;

Outer JoinCode as the following

Select * from a full (left/right) Outer Join B on a on A. categoryid = B. categoryid;

Left/right Outer Join Claus specificMSSQL:
Select * From A, B where a. categoryid * = bcategoryid;
Elect * From A, B where a. categoryid = * B. categoryid;

Left/right Outer Join Claus specificOracle:
Select * From A, B where a. categoryid = B. categoryid (+ );
Select * From A, B where a. categoryid (+) = B. categoryid;

Good resources:
Http://www.w3schools.com/ SQL/SQL _join.asp
Http://www.techonthenet.com/ SQL /joins.htm