How to have the subquery select from a different table than the parent statement : Nested Subquery « Query Select « Oracle PL/SQL Tutorial

1. Oracle PL/SQL Tutorial
2. Query Select
3. Nested Subquery

SQL> --
SQL>
SQL>
SQL> CREATE TABLE product_order (
  2       product_name  VARCHAR2(25),
  3       salesperson   VARCHAR2(3),
  4       order_date    DATE,
  5       quantity      NUMBER(4,2)
  6  );

Table created.

SQL>
SQL> CREATE TABLE person (
  2       person_code VARCHAR2(3) PRIMARY KEY,
  3       first_name  VARCHAR2(15),
  4       last_name   VARCHAR2(20),
  5       hire_date   DATE
  6  );

Table created.

SQL>
SQL>
SQL> INSERT INTO person VALUES ('CA', 'Chase', 'At',    '01-FEB-02');

1 row created.

SQL> INSERT INTO person VALUES ('GA', 'Gary',  'Talor', '15-FEB-02');

1 row created.

SQL> INSERT INTO person VALUES ('BB', 'Bob',   'Bark',  '28-FEB-02');

1 row created.

SQL> INSERT INTO person VALUES ('LB', 'Laren', 'Baby',  '01-MAR-02');

1 row created.

SQL> INSERT INTO person VALUES ('LN', 'Linda', 'Norman','01-JUN-03');

1 row created.

SQL>
SQL>
SQL> INSERT INTO product_order VALUES ('Product 1', 'CA', '14-JUL-03', 1);

1 row created.

SQL> INSERT INTO product_order VALUES ('Product 2', 'BB', '14-JUL-03', 75);

1 row created.

SQL> INSERT INTO product_order VALUES ('Product 3', 'GA', '14-JUL-03', 2);

1 row created.

SQL> INSERT INTO product_order VALUES ('Product 4', 'GA', '15-JUL-03', 8);

1 row created.

SQL> INSERT INTO product_order VALUES ('Product 5', 'LB', '15-JUL-03', 20);

1 row created.

SQL> INSERT INTO product_order VALUES ('Product 6', 'CA', '16-JUL-03', 5);

1 row created.

SQL> INSERT INTO product_order VALUES ('Product 7', 'CA', '17-JUL-03', 1);

1 row created.

SQL>
SQL>
SQL> SELECT * FROM product_order
  2  WHERE  salesperson = (
  3         SELECT person_code
  4         FROM   person
  5         WHERE  first_name = 'Gary' AND last_name = 'Anderson'
  6  );

no rows selected

SQL>
SQL> drop table product_order;

Table dropped.

SQL> drop table person;

Table dropped.