OUTER JOIN

    =>    Equi JOIN returns only matching records but doesn't return un-matched records.
    =>    To get the un-matched records also we need to perform Outer Join.
    =>    Outer join is of 3 types:
            (a)    Left Outer
            (b)    Right Outer
            (c)    Full Outer

    a) Left Outer Join:
    =>    It returns all the records from Left side table and matching records from Right side table.
   
    Syntax:
    =>    Select <collist> from <tablelist>  where <cond1> = <cond2> (+)
    =>    Select <collist> from <table1>  LEFT OUTER JOIN <table2> ON <join condition>

    Examples:

    1. Display all the employee records and their respective dept names ?
    =>    Select e.ename, d.dname from emp e, dept d where e.deptno = d.deptno (+);
            (or)
    =>    Select e.ename, d.dname from emp e LEFT OUTER JOIN dept d ON ( e.deptno = d.deptno )
            (or)
    =>    Select e.ename , d.dname from emp e LEFT OUTER JOIN dept d USING( deptno );

   
    b) Right Outer Join:
    =>    It returns all the records Right side table and matching records from Left side table.

    Syntax:
    =>    Select <collist> from <tablelist>  where <cond1> (+)= <cond2>
    =>    Select <collist> from <table1>  RIGHT OUTER JOIN <table2> ON <join condition>

    Examples:

    1. Display all the dept records and their respective employees ?
    =>    Select d.dname,e.ename from dept d, emp e where d.deptno (+)= e.deptno ;
            (or)
    =>    Select d.dname,e.ename from dept d RIGHT OUTER JOIN emp e ON ( d.deptno = e.deptno )
            (or)
    =>    Select d.dname,e.ename from dept d RIGHT OUTER JOIN emp e USING( deptno )

   
    c) Full Outer Join:
    =>    It return all records from both the tables.
    =>    It doesn't support NON-ASCII JOIN.

    Syntax:
    =>    Select <collist> from <table1> FULL OUTER JOIN <table2> ON <join condition>

    Examples:

    1. Display all the employee records and dept records.
    =>    Select e.ename, d.dname from emp e
            FULL OUTER JOIN dept d USING( deptno );