Exist with subquery : EXISTS « Query Select « Oracle PL/SQL Tutorial

1. Oracle PL/SQL Tutorial
2. Query Select
3. EXISTS

SQL>
SQL> create table course_schedule
  2  ( course     VARCHAR2(6)
  3  , begindate  DATE
  4  , trainer    NUMBER(4)
  5  , location   VARCHAR2(20)) ;

Table created.

SQL>
SQL>
SQL> insert into course_schedule values ('SQL',date '1999-04-12',1,'VANCOUVER' );

1 row created.

SQL> insert into course_schedule values ('OAU',date '1999-08-10',2,'CHICAGO');

1 row created.

SQL> insert into course_schedule values ('SQL',date '1999-10-04',3,'SEATTLE');

1 row created.

SQL> insert into course_schedule values ('SQL',date '1999-12-13',4,'DALLAS' );

1 row created.

SQL> insert into course_schedule values ('JAV',date '1999-12-13',5,'SEATTLE');

1 row created.

SQL> insert into course_schedule values ('XML',date '2000-02-03',6,'VANCOUVER' );

1 row created.

SQL> insert into course_schedule values ('JAV',date '2000-02-01',7,'DALLAS' );

1 row created.

SQL> insert into course_schedule values ('PLS',date '2000-09-11',8,'VANCOUVER' );

1 row created.

SQL> insert into course_schedule values ('XML',date '2000-09-18',NULL,'SEATTLE');

1 row created.

SQL> insert into course_schedule values ('OAU',date '2000-09-27',9,'DALLAS' );

1 row created.

SQL> insert into course_schedule values ('ERM',date '2001-01-15',10, NULL    );

1 row created.

SQL> insert into course_schedule values ('PRO',date '2001-02-19',NULL,'VANCOUVER' );

1 row created.

SQL> insert into course_schedule values ('RSD',date '2001-02-24',8,'CHICAGO');

1 row created.

SQL>
SQL> create table employees(
  2    empno      NUMBER(4)
  3  , ename      VARCHAR2(8)
  4  , init       VARCHAR2(5)
  5  , job        VARCHAR2(8)
  6  , mgr        NUMBER(4)
  7  , bdate      DATE
  8  , msal       NUMBER(6,2)
  9  , comm       NUMBER(6,2)
 10  , deptno     NUMBER(2) ) ;

Table created.

SQL>
SQL>
SQL> insert into employees values(1,'Jason',  'N',  'TRAINER', 2,   date '1965-12-18',  800 , NULL,  10);

1 row created.

SQL> insert into employees values(2,'Jerry',  'J',  'SALESREP',3,   date '1966-11-19',  1600, 300,   10);

1 row created.

SQL> insert into employees values(3,'Jord',   'T' , 'SALESREP',4,   date '1967-10-21',  1700, 500,   20);

1 row created.

SQL> insert into employees values(4,'Mary',   'J',  'MANAGER', 5,   date '1968-09-22',  1800, NULL,  20);

1 row created.

SQL> insert into employees values(5,'Joe',    'P',  'SALESREP',6,   date '1969-08-23',  1900, 1400,  30);

1 row created.

SQL> insert into employees values(6,'Black',  'R',  'MANAGER', 7,   date '1970-07-24',  2000, NULL,  30);

1 row created.

SQL> insert into employees values(7,'Red',    'A',  'MANAGER', 8,   date '1971-06-25',  2100, NULL,  40);

1 row created.

SQL> insert into employees values(8,'White',  'S',  'TRAINER', 9,   date '1972-05-26',  2200, NULL,  40);

1 row created.

SQL> insert into employees values(9,'Yellow', 'C',  'DIRECTOR',10,  date '1973-04-27',  2300, NULL,  20);

1 row created.

SQL> insert into employees values(10,'Pink',  'J',  'SALESREP',null,date '1974-03-28',  2400, 0,     30);

1 row created.

SQL>
SQL>
SQL>
SQL> select e.*
  2  from   employees e
  3  where  exists (select o.*
  4                 from   course_schedule o
  5                 where  o.course = 'SQL'
  6                 and    o.trainer = e.empno);

     EMPNO ENAME    INIT  JOB             MGR BDATE           MSAL       COMM     DEPTNO
---------- -------- ----- -------- ---------- --------- ---------- ---------- ----------
         1 Jason    N     TRAINER           2 18-DEC-65        800                    10
         3 Jord     T     SALESREP          4 21-OCT-67       1700        500         20
         4 Mary     J     MANAGER           5 22-SEP-68       1800                    20

SQL>
SQL> drop table employees;

Table dropped.

SQL>
SQL> drop table course_schedule;

Table dropped.

SQL>