How to concatenate columns in a Postgres SELECT?

Question

I have two string columns a and b in a table foo.

select a, b from foo returns values a and b<

Answer 1

For example if there is employee table which consists of columns as:

employee_number,f_name,l_name,email_id,phone_number 

if we want to concatenate f_name + l_name as name.

SELECT employee_number,f_name ::TEXT ||','|| l_name::TEXT  AS "NAME",email_id,phone_number,designation FROM EMPLOYEE;