PostgreSQL - AND, OR, & NOT Operators

The PostgreSQL WHERE clause conditions can be combined using AND, OR, and NOT operators. These operators are used to handle more than one conditions.

• AND - Used to combine multiple conditions and displays a record if all the conditions separated by AND operator are true.
• OR - Used to combine multiple conditions and displays a record if any of the conditions separated by OR operator is true.
• NOT - Used to display a record where the specified condition is not true.

Syntax

The syntax for using these operators in PostgreSQL are given below:

/* AND Operator */
SELECT column1, column2, column3, ...
FROM table_name
WHERE condition1 AND condition2 AND condtion3 ....;

/* OR Operator */
SELECT column1, column2, column3, ...
FROM table_name
WHERE condition1 OR condition2 OR condtion3 ....;

/* NOT Operator */
SELECT column1, column2, column3, ...
FROM table_name
WHERE NOT condition;

Example:

Consider a database table called Employee with the following records:

• AND Example: To select all records of the Employee table where Salary is greater than 2800 and Age is less than 30, the query is mentioned below.

  SELECT * FROM Employee
  WHERE Salary > 2800 AND Age < 30;
  

  
  

  This result of the following code will be:

  EmpID	Name	City	Age	Salary
  1	John	London	25	3000
  5	Ramesh	New Delhi	28	3000

• OR Example: To select all records of the Employee table where Salary is greater than 2800 or Age is less than 25, the query is given below.

  SELECT * FROM Employee
  WHERE Salary > 2800 OR Age < 25;
  

  
  

  This will produce the result as shown below:

  EmpID	Name	City	Age	Salary
  1	John	London	25	3000
  2	Marry	New York	24	2750
  4	Kim	Amsterdam	30	3100
  5	Ramesh	New Delhi	28	3000

• NOT Example: To select all records of the Employee table where City is NOT "New Delhi", the query is given below.

  SELECT * FROM Employee
  WHERE NOT City = 'New Delhi';
  

  
  

  This result of the query is shown below:

  EmpID	Name	City	Age	Salary
  1	John	London	25	3000
  2	Marry	New York	24	2750
  3	Jo	Paris	27	2800
  4	Kim	Amsterdam	30	3100
  6	Huang	Beijing	28	2800