Outer join syntax is hard to remember. Make up some mnemonics to help.

SQL> select * from emp;

        ID NAME           DEPTID
---------- ---------- ----------
         1 John                1

SQL> select * from dept;

        ID NAME
---------- ----------
         1 Accounting
         2 IT

SQL> select * from emp a, dept b where a.deptid=b.id(+);

        ID NAME           DEPTID         ID NAME
---------- ---------- ---------- ---------- ----------
         1 John                1          1 Accounting

SQL> select * from emp a, dept b where a.deptid(+)=b.id; <-- think of "(+)" as "plus something else", "plus more rows"

        ID NAME           DEPTID         ID NAME
---------- ---------- ---------- ---------- ----------
         1 John                1          1 Accounting   <-- table A (emp) row
                                          2 IT           <-- plus rows from other tables (even if not matching)

SQL> select * from emp a left outer join dept b on a.deptid=b.id;

        ID NAME           DEPTID         ID NAME
---------- ---------- ---------- ---------- ----------
         1 John                1          1 Accounting

SQL> select * from emp a right outer join dept b on a.deptid=b.id; <-- same as "from a, b where a.deptid(+)=b.id"
                                                                    -- think of "right outer" as "plus something else"
        ID NAME           DEPTID         ID NAME
---------- ---------- ---------- ---------- ----------
         1 John                1          1 Accounting   <-- table A (emp) row
                                          2 IT           <-- plus rows from other tables (even if not matching)

SQL> select * from dept a left outer join emp b on a.id=b.deptid; <-- think of "left outer" as "show all rows"
                                                                   -- i.e. "show all rows (even if not matching)"
        ID NAME               ID NAME           DEPTID             -- read "a left outer join b" as "A showing all rows
---------- ---------- ---------- ---------- ----------             -- "(even if not matching) join B"
         1 Accounting          1 John                1
         2 IT

SQL> select * from dept a right outer join emp b on a.id=b.deptid;

        ID NAME               ID NAME           DEPTID
---------- ---------- ---------- ---------- ----------
         1 Accounting          1 John                1

SQL> select * from dept a left join emp b on a.id=b.deptid; <-- "outer" in "left outer" or "right outer" is optional
                                                             -- but it's better to keep it for easy reading
        ID NAME               ID NAME           DEPTID
---------- ---------- ---------- ---------- ----------
         1 Accounting          1 John                1
         2 IT