外连接运算符（+）
vastbase=# select d.deptno,dname,empno,ename from dept d,emp e where
d.deptno=e.deptno(+);
deptno | dname | empno | ename
--------+------------+-------+--------
10 | ACCOUNTING | 7934 | MILLER
10 | ACCOUNTING | 7839 | KING
10 | ACCOUNTING | 7782 | CLARK
20 | RESEARCH | 7902 | FORD
20 | RESEARCH | 7566 | JONES
20 | RESEARCH | 7369 | SMITH
30 | SALES | 7900 | JAMES
30 | SALES | 7844 | TURNER
30 | SALES | 7698 | BLAKE
30 | SALES | 7654 | MARTIN
30 | SALES | 7521 | WARD
30 | SALES | 7499 | ALLEN
40 | OPERATIONS | |
(13 rows)
