CREATE OR REPLACE VIEW v AS
SELECT * FROM emp WHERE deptno != 10
UNION ALL
SELECT * FROM emp WHERE ename = 'WARD';
SQL> set linesize 200
SQL> select * from v where v.ename='WARD';
EMPNO ENAME JOB MGR HIREDATE SAL COMM DEPTNO
---------- ---------- ---------- ---------- -------------- ---------- ---------- ----------
7521 WARD SALESMAN 7698 22-2月 -81 1250 500 30
7521 WARD SALESMAN 7698 22-2月 -81 1250 500 30
SQL> select * from emp where ename='WARD';
EMPNO ENAME JOB MGR HIREDATE SAL COMM DEPTNO
---------- ---------- ---------- ---------- -------------- ---------- ---------- ----------
7521 WARD SALESMAN 7698 22-2月 -81 1250 500 30
用全关联的话:
SQL> SELECT v.empno, v.ename, b.empno, b.ename
FROM v
FULL JOIN emp b ON (b.empno = v.empno)
WHERE (v.empno IS NULL OR b.empno IS NULL); 2 3 4
EMPNO ENAME EMPNO ENAME
---------- ---------- ---------- ----------
7839 KING
7782 CLARK
7934 MILLER
会丢失ENAME=WARD的数据,可以使用标量子查询:
SQL> SELECT empno,ename,job,mgr,hiredate,sal,comm,deptno,
/*这儿使用的语句就叫标量子查询，以主表返回每一行的值为条件进行查询*/
(SELECT COUNT(*) FROM v v2 WHERE v2.empno = v.empno) AS cnt
FROM v 2 3 4 ;
EMPNO ENAME JOB MGR HIREDATE SAL COMM DEPTNO CNT
---------- ---------- ---------- ---------- -------------- ---------- ---------- ---------- ----------
7369 SMITH CLERK 7902 17-12月-80 800 20 1
7499 ALLEN SALESMAN 7698 20-2月 -81 1600 300 30 1
7521 WARD SALESMAN 7698 22-2月 -81 1250 500 30 2
7566 JONES MANAGER 7839 02-4月 -81 2975 20 1
7654 MARTIN SALESMAN 7698 28-9月 -81 1250 1400 30 1
7698 BLAKE MANAGER 7839 01-5月 -81 2850 30 1
7788 SCOTT ANALYST 7566 09-12月-82 3000 20 1
7844 TURNER SALESMAN 7698 08-9月 -81 1500 0 30 1
7876 ADAMS CLERK 7788 12-1月 -83 1100 20 1
7900 JAMES CLERK 7698 03-12月-81 950 30 1
7902 FORD ANALYST 7566 03-12月-81 3000 20 1
EMPNO ENAME JOB MGR HIREDATE SAL COMM DEPTNO CNT
---------- ---------- ---------- ---------- -------------- ---------- ---------- ---------- ----------
7521 WARD SALESMAN 7698 22-2月 -81 1250 500 30 2
已选择12行。
SQL> SELECT empno,ename,job,mgr,hiredate,sal,comm,deptno,
(SELECT COUNT(*) FROM emp b WHERE b.empno = emp.empno) AS cnt
FROM emp 2 3 ;
EMPNO ENAME JOB MGR HIREDATE SAL COMM DEPTNO CNT
---------- ---------- ---------- ---------- -------------- ---------- ---------- ---------- ----------
7369 SMITH CLERK 7902 17-12月-80 800 20 1
7499 ALLEN SALESMAN 7698 20-2月 -81 1600 300 30 1
7521 WARD SALESMAN 7698 22-2月 -81 1250 500 30 1
7566 JONES MANAGER 7839 02-4月 -81 2975 20 1
7654 MARTIN SALESMAN 7698 28-9月 -81 1250 1400 30 1
7698 BLAKE MANAGER 7839 01-5月 -81 2850 30 1
7782 CLARK MANAGER 7839 09-6月 -81 2450 10 1
7788 SCOTT ANALYST 7566 09-12月-82 3000 20 1
7839 KING PRESIDENT 17-11月-81 5000 10 1
7844 TURNER SALESMAN 7698 08-9月 -81 1500 0 30 1
7876 ADAMS CLERK 7788 12-1月 -83 1100 20 1
EMPNO ENAME JOB MGR HIREDATE SAL COMM DEPTNO CNT
---------- ---------- ---------- ---------- -------------- ---------- ---------- ---------- ----------
7900 JAMES CLERK 7698 03-12月-81 950 30 1
7902 FORD ANALYST 7566 03-12月-81 3000 20 1
7934 MILLER CLERK 7782 23-1月 -82 1300 10 1
已选择14行。
SQL> SELECT v.empno, v.ename, v.cnt, emp.empno, emp.ename, emp.cnt
FROM (SELECT empno,ename,job,mgr,hiredate,sal,comm,deptno,
/*这儿使用的语句就叫标量子查询，以主表返回每一行的值为条件进行查询*/
(SELECT COUNT(*) FROM v v2 WHERE v2.empno = v.empno) AS cnt
FROM v) v
FULL JOIN (SELECT empno,ename,job,mgr,hiredate,sal,comm,deptno,
(SELECT COUNT(*) FROM emp b WHERE b.empno = emp.empno) AS cnt
FROM emp) emp
ON (emp.empno = v.empno AND emp.cnt = v.cnt)
WHERE (v.empno IS NULL OR emp.empno IS NULL); 2 3 4 5 6 7 8 9 10
EMPNO ENAME CNT EMPNO ENAME CNT
---------- ---------- ---------- ---------- ---------- ----------
7521 WARD 2
7521 WARD 2
7521 WARD 1
7782 CLARK 1
7839 KING 1
7934 MILLER 1
已选择6行。
