PostgreSQL - Comparison Operators

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Consider the table COMPANY having records as follows:

testdb=# select * from COMPANY;
 id | name  | age | address   | salary
----+-------+-----+-----------+--------
  1 | Paul  |  32 | California|  20000
  2 | Allen |  25 | Texas     |  15000
  3 | Teddy |  23 | Norway    |  20000
  4 | Mark  |  25 | Rich-Mond |  65000
  5 | David |  27 | Texas     |  85000
  6 | Kim   |  22 | South-Hall|  45000
  7 | James |  24 | Houston   |  10000
(7 rows)

Here are simple examples showing usage of PostgresSQL Comparison Operators:

Here, we have used WHERE clause, which will be explained in a separate chapter but for now you can understand that WHERE clause is used to put a conditional statement along with SELECT statement.

Following SELECT statement lists down all the records having SALARY greater than 50,000.00:

testdb=# SELECT * FROM COMPANY WHERE SALARY > 50000;

Above PostgreSQL statement will produce the following result:

 id | name  | age |address    | salary
----+-------+-----+-----------+--------
  4 | Mark  |  25 | Rich-Mond |  65000
  5 | David |  27 | Texas     |  85000
(2 rows)

Following SELECT statement lists down all the records having SALARY equal to 20,000.00:

testdb=#  SELECT * FROM COMPANY WHERE SALARY = 20000;

Above PostgreSQL statement will produce the following result:

  id | name  | age |  address    | salary
 ----+-------+-----+-------------+--------
   1 | Paul  |  32 | California  |  20000
   3 | Teddy |  23 | Norway      |  20000
(2 rows)

Following SELECT statement lists down all the records having SALARY not equal to 20,000.00:

testdb=#  SELECT * FROM COMPANY WHERE SALARY != 20000;

Above PostgreSQL statement will produce the following result:

 id | name  | age |  address    | salary
----+-------+-----+-------------+--------
  2 | Allen |  25 | Texas       |  15000
  4 | Mark  |  25 | Rich-Mond   |  65000
  5 | David |  27 | Texas       |  85000
  6 | Kim   |  22 | South-Hall  |  45000
  7 | James |  24 | Houston     |  10000
(5 rows)

Following SELECT statement lists down all the records having SALARY not equal to 20,000.00:

testdb=# SELECT * FROM COMPANY WHERE SALARY <> 20000;

Above PostgreSQL statement will produce the following result:

 id | name  | age | address    | salary
----+-------+-----+------------+--------
  2 | Allen |  25 | Texas      |  15000
  4 | Mark  |  25 | Rich-Mond  |  65000
  5 | David |  27 | Texas      |  85000
  6 | Kim   |  22 | South-Hall |  45000
  7 | James |  24 | Houston    |  10000
(5 rows)

Following SELECT statement lists down all the records having SALARY greater than or equal to 65,000.00:

testdb=# SELECT * FROM COMPANY WHERE SALARY >= 65000;

Above PostgreSQL statement will produce the following result:

 id | name  | age |  address  | salary
----+-------+-----+-----------+--------
  4 | Mark  |  25 | Rich-Mond |  65000
  5 | David |  27 | Texas     |  85000
(2 rows)


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