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SQL> -- create demo table
SQL>
SQL> CREATE TABLE EMP (EMPNO NUMBER(4) NOT NULL,
2 ENAME VARCHAR2(10),
3 JOB VARCHAR2(9),
4 MGR NUMBER(4),
5 HIREDATE DATE,
6 SAL NUMBER(7, 2),
7 COMM NUMBER(7, 2),
8 DEPTNO NUMBER(2));
Table created.
SQL>
SQL> INSERT INTO EMP VALUES (7369, 'SMITH', 'CLERK', 7902, TO_DATE('17-DEC-1980', 'DD-MON-YYYY'), 800, NULL, 20);
1 row created.
SQL> INSERT INTO EMP VALUES (7499, 'ALLEN', 'SALESMAN', 7698, TO_DATE('20-FEB-1981', 'DD-MON-YYYY'), 1600, 300, 30);
1 row created.
SQL> INSERT INTO EMP VALUES (7521, 'WARD', 'SALESMAN', 7698, TO_DATE('22-FEB-1981', 'DD-MON-YYYY'), 1250, 500, 30);
1 row created.
SQL> INSERT INTO EMP VALUES (7566, 'JONES', 'MANAGER', 7839, TO_DATE('2-APR-1981', 'DD-MON-YYYY'), 2975, NULL, 20);
1 row created.
SQL> INSERT INTO EMP VALUES (7654, 'MARTIN', 'SALESMAN', 7698,TO_DATE('28-SEP-1981', 'DD-MON-YYYY'), 1250, 1400, 30);
1 row created.
SQL> INSERT INTO EMP VALUES (7698, 'BLAKE', 'MANAGER', 7839,TO_DATE('1-MAY-1981', 'DD-MON-YYYY'), 2850, NULL, 30);
1 row created.
SQL> INSERT INTO EMP VALUES (7782, 'CLARK', 'MANAGER', 7839,TO_DATE('9-JUN-1981', 'DD-MON-YYYY'), 2450, NULL, 10);
1 row created.
SQL> INSERT INTO EMP VALUES (7788, 'SCOTT', 'ANALYST', 7566,TO_DATE('09-DEC-1982', 'DD-MON-YYYY'), 3000, NULL, 20);
1 row created.
SQL> INSERT INTO EMP VALUES (7839, 'KING', 'PRESIDENT', NULL,TO_DATE('17-NOV-1981', 'DD-MON-YYYY'), 5000, NULL, 10);
1 row created.
SQL> INSERT INTO EMP VALUES (7844, 'TURNER', 'SALESMAN', 7698,TO_DATE('8-SEP-1981', 'DD-MON-YYYY'), 1500, 0, 30);
1 row created.
SQL> INSERT INTO EMP VALUES (7876, 'ADAMS', 'CLERK', 7788,TO_DATE('12-JAN-1983', 'DD-MON-YYYY'), 1100, NULL, 20);
1 row created.
SQL> INSERT INTO EMP VALUES (7900, 'JAMES', 'CLERK', 7698,TO_DATE('3-DEC-1981', 'DD-MON-YYYY'), 950, NULL, 30);
1 row created.
SQL> INSERT INTO EMP VALUES (7902, 'FORD', 'ANALYST', 7566,TO_DATE('3-DEC-1981', 'DD-MON-YYYY'), 3000, NULL, 20);
1 row created.
SQL> INSERT INTO EMP VALUES (7934, 'MILLER', 'CLERK', 7782,TO_DATE('23-JAN-1982', 'DD-MON-YYYY'), 1300, NULL, 10);
1 row created.
SQL>
SQL> select * from emp;
EMPNO ENAME JOB MGR HIREDATE SAL COMM DEPTNO
---------- ---------- --------- ---------- ----------- ---------- ---------- ----------
7369 SMITH CLERK 7902 1980-DEC-17 800 20
7499 ALLEN SALESMAN 7698 1981-FEB-20 1600 300 30
7521 WARD SALESMAN 7698 1981-FEB-22 1250 500 30
7566 JONES MANAGER 7839 1981-APR-02 2975 20
7654 MARTIN SALESMAN 7698 1981-SEP-28 1250 1400 30
7698 BLAKE MANAGER 7839 1981-MAY-01 2850 30
7782 CLARK MANAGER 7839 1981-JUN-09 2450 10
7788 SCOTT ANALYST 7566 1982-DEC-09 3000 20
7839 KING PRESIDENT 1981-NOV-17 5000 10
7844 TURNER SALESMAN 7698 1981-SEP-08 1500 0 30
7876 ADAMS CLERK 7788 1983-JAN-12 1100 20
7900 JAMES CLERK 7698 1981-DEC-03 950 30
7902 FORD ANALYST 7566 1981-DEC-03 3000 20
7934 MILLER CLERK 7782 1982-JAN-23 1300 10
14 rows selected.
SQL>
SQL> --Performing Self Joins Using SQL/92
SQL>
SQL> --The following example uses SQL/86 to perform a self join on the employees table:
SQL>
SQL> SELECT e.ename || ' works for ' || m.ename
2 FROM emp e, emp m
3 WHERE e.mgr = m.empno;
E.ENAME||'WORKSFOR'||M.ENAME
-------------------------------
FORD works for JONES
SCOTT works for JONES
JAMES works for BLAKE
TURNER works for BLAKE
MARTIN works for BLAKE
WARD works for BLAKE
ALLEN works for BLAKE
MILLER works for CLARK
ADAMS works for SCOTT
CLARK works for KING
BLAKE works for KING
JONES works for KING
SMITH works for FORD
13 rows selected.
SQL>
SQL> -- The next example rewrites this query to use the SQL/92 INNER JOIN and ON keywords:
SQL>
SQL> SELECT w.ename || ' works for ' || m.ename
2 FROM emp w INNER JOIN emp m
3 ON w.mgr = m.empno;
W.ENAME||'WORKSFOR'||M.ENAME
-------------------------------
FORD works for JONES
SCOTT works for JONES
JAMES works for BLAKE
TURNER works for BLAKE
MARTIN works for BLAKE
WARD works for BLAKE
ALLEN works for BLAKE
MILLER works for CLARK
ADAMS works for SCOTT
CLARK works for KING
BLAKE works for KING
JONES works for KING
SMITH works for FORD
13 rows selected.
SQL>
SQL>
SQL>
SQL> drop table Emp
2 /
Table dropped.
SQL>
SQL>
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