Column Alias in PostgreSQL

In this article I will share how we can assign a column alias and it's in the PostgreSQL.
Let's get started...
Column alias is used to assign a temporary name to a column or an expression in the PostgreSQL. It exists only temporarily during the execution of query.

Syntax of using a Column Alias

SELECT column_name AS alias_name
FROM table_name;

As from the syntax, it can be seen that column_name is assigned an alias alias_name. Here AS key is used to assign the alias name. AS key is optional to use. We can omit it as well. The syntax will be then as:

SELECT column_name alias_name
FROM table_name;

Example
Suppose we have the customer table with following attributes in the database:

1. Assigning a column alias to a column:

SELECT 
   first_name, 
   last_name AS surname
FROM customer;

The above query assigned the surname as column alias to the last_name. If we have not used column alias then the name of the column would have appeared as "last_name".

OUTPUT:

2. Assigning a column alias to an expression:

SELECT 
   first_name || ' ' || last_name AS full_name 
FROM 
   customer;

The above query returns full names of all the customers. The expression first_name || ' ' || last_name AS full_name constructs the full name by concatenating the first name, space and the last name.

OUTPUT:

Conclusion
In this tutorial we learnt about how we can assign temporary names to the queries using AS in our query statement.