Using EXISTS with a Correlated Subquery : Correlated Subquery « Subquery « Oracle PL / SQL

1. Oracle PL / SQL
2. Subquery
3. Correlated Subquery

Using EXISTS with a Correlated Subquery

  


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> --Using EXISTS with a Correlated Subquery
SQL>
SQL> SELECT empno, ename
  2  FROM emp outer
  3  WHERE EXISTS
  4    (SELECT empno
  5     FROM emp inner
  6     WHERE inner.mgr = outer.empno);

     EMPNO ENAME
---------- ----------
      7902 FORD
      7698 BLAKE
      7839 KING
      7566 JONES
      7788 SCOTT
      7782 CLARK

6 rows selected.

SQL>
SQL> drop table emp;

Table dropped.

SQL>
SQL>
           
         
    
  

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