Syntax
Inner:
1. <TableExpression> [INNER] JOIN <TableExpression> ON <BooleanExpression>
2. Implicit Syntax: select * a, b where a.id = b.id;
Left Outer:
1. <TableExpression> LEFT [OUTER] JOIN <TableExpression> ON <BooleanExpression>
2. Using + operator. select * from table a, b where a.id+ = b.id (Oracle)
3. Using * operator. select * from table a, b where a.id *= b.id
Full Outer Join
1. <TableExpression> FULL [OUTER] JOIN <TableExpression> ON <BooleanExpression>
Note: Oracle recommends to use OUTER JOIN SYNTAX than to use operator (+).
References:
1. http://docs.oracle.com/cd/B19306_01/server.102/b14200/queries006.htm
2. http://docs.oracle.com/javadb/10.6.2.1/ref/rrefsqlj29840.html#rrefsqlj29840