PostgreSQL: Using Column Aliases for Readable Queries

Improve the readability of your PostgreSQL queries by using column aliases. This guide explains how to assign temporary names to columns in result sets.

Using Column Aliases in PostgreSQL

PostgreSQL column aliases provide a way to give temporary, more descriptive names to columns in the result set of a `SELECT` query. This improves the readability and understandability of your query results.

Understanding Column Aliases

Column aliases are temporary names assigned to columns within a specific SQL query. They are particularly useful when column names are long, unclear, or need to be customized for presentation purposes. Aliases are only valid for the duration of the query's execution; they do not change the underlying column names in the table.

Syntax for Column Aliases

There are several ways to create aliases:

Syntax 1: Using `AS` (Recommended)

SELECT column_name AS alias_name FROM table_name;

Syntax 2: Omitting `AS`

SELECT column_name alias_name FROM table_name;

Syntax 3: Aliasing Expressions

SELECT expression AS alias_name FROM table_name;

The `AS` keyword is optional in most cases.

Example 1: Renaming a Column

(Note: This example assumes an `employee` table exists with columns `emp_fname` and `emp_lname`. Screenshots from the original text are not included here. Please refer to the original document for visual verification of the examples. The descriptions below aim to convey the information in those screenshots.)

SELECT emp_fname, emp_lname AS last_name FROM employees;

Example 2: Aliasing an Expression

This example concatenates the first and last names and assigns it an alias:

SELECT first_name || ' ' || last_name AS "Full Name" FROM employees;

Note that when the alias contains spaces, you must enclose it in double quotes.