PostgreSQL - WHERE Clause

The PostgreSQL WHERE Clause is used to specify condition(s) in a query. It can be used to specify condition(s) while fetching data from a table, joining two tables, updating records in a table, inserting records in a table or deleting records from a table.

Syntax

The syntax for using WHERE Clause in PostgreSQL is given below:

SELECT column1, column2, ...
FROM table_name
WHERE condition(s);

To specify condition in a query, comparison or logical operators like <, >, =, LIKE, IN, NOT, NULL etc. are used.

Example:

Consider a database containing a table called Employee with the following records:

• To fetch Name, Age and Salary data from Employee table where Salary is greater than 2800, the query is:

  SELECT Name, Age, Salary 
  FROM Employee
  WHERE Salary > 2800;
  

  
  

  This will produce the result as shown below:

  Name	Age	Salary
  John	25	3000
  Kim	30	3100
  Ramesh	28	3000

• To specify multiple conditions logical operators are used, for example - To fetch data from the Employee table where Salary is greater than 2800 and Age is less than 30, the PostgreSQL AND operator is used and the query will be:

  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