How to Use a SQL Alias to Simplify Your Queries

A SQL alias is a temporary name for a table or column in an SQL query. It is usually used to simplify a complex query by making it easily readable or simply giving a column a more human-readable or natural-sounding name. In this article, I will discuss the different techniques and practical applications of using an SQL alias.

Before we get started, I recommend taking DataCamp’s Introduction to SQL course to gain foundational knowledge in SQL. The SQL Basics Cheat Sheet will also help you refresh basic SQL concepts during your learning.

What is a SQL Alias?

A SQL alias improves the readability of a query. Assume you have two tables, Products and Suppliers.

Example of Products table to rename columns using SQL alias. Image by Author.

Example of Suppliers table to rename columns using SQL alias. Image by Author.

The following query uses the AS keyword to create an alias, which renames a column in the Products table.

-- Select the product_name column from the Products table and alias it as 'Product'
-- Select the price column from the Products table and alias it as 'Price'
SELECT product_name AS Product, 
       price AS Price
FROM Products;

Using the AS Keyword to Create a SQL Alias

SQL aliases are important when renaming long column names or joining multiple tables. The SQL alias syntax uses the AS keyword to rename the column or table. However, the AS keyword is optional, provided you indicate the table or column alias.

What is convenient is that different SQL databases, including MySQL, PostgreSQL, and SQL Server, fully support the SQL alias for table and column names, so you don’t need to memorize different database-specific methods.

Example of SQL column alias

The syntax below shows the SQL column alias using the AS keyword.

SELECT column_name AS alias_name
FROM table_name;

The query below produces the same output because the AS keyword is optional. 

SELECT column_name alias_name
FROM table_name;

Example of a SQL table alias

The syntax below shows the SQL table alias using the AS keyword.

SELECT column1, column2
FROM table_name AS alias_name;

The following syntax shows the table alias without the AS keyword.

SELECT column1, column2
FROM table_name alias_name;

When to Use a SQL Alias

The SQL alias has the following applications.

• Making Reports and Dashboards More Clear : Aliases are used to rename columns to include meaningful names, improving understanding of reports. 
• Helping the Coding Process: A SQL alias is especially useful when merging columns in tables to improve data clarity.
• Enhancing Collaborative Projects: Using a SQL alias improves collaboration in a team because it helps create consistent naming conventions of tables and columns in a database.

I recommend taking DataCamp’s Reporting in SQL course to learn more about building dashboards and incorporating SQL aliases to create interactive reports. I also recommend checking out our SQL Fundamentals skill track to learn advanced SQL methods, including joining data in more advanced ways.

SQL Alias Examples and Use Cases

The following examples show how to use SQL aliases to rename columns and tables in queries.

Using a SQL alias for column names

The SQL alias can be used to rename column names. Using aliases in columns improves query readability by making complex queries clear. In the example below, SQL aliases have been used to rename two columns: product_name has become Product, and price has become Price.

-- Select and alias columns
SELECT product_name AS Product, 
       price AS Price
FROM Products;

Example output of SQL column alias. Image by Author.

Using a SQL alias for table names

The SQL alias can also be used to temporarily rename tables. This technique simplifies complex queries when working with multiple tables. The query below shows how to use table alias when joining two tables. The table aliases improve query readability by shortening the table names. This is really useful when joining two tables together.

-- Select product names and supplier names
SELECT p.product_name, 
       s.supplier_name
-- From the Products table aliased as 'p'
FROM Products AS p
-- Join with the Suppliers table aliased as 's' on matching supplier_id
JOIN Suppliers AS s ON p.supplier_id = s.supplier_id;

Example output of SQL table alias. Image by Author.

Adhere to the following best practices when using table aliases in complex joins and subqueries. First, use short and descriptive aliases to improve clarity and readability. Second, use different names for columns and tables to avoid name conflicts and ambiguity.

Applying more than one SQL alias

You can combine SQL aliases for column and table names in a single query. This technique is helpful for subqueries and other complex queries. The query below uses a SQL alias for both columns and tables. It will retrieve the product_name and supplier_name for those located in New York City.

-- Select product names from the Products table and alias as 'Product'
-- Select supplier names from the subquery and alias as 'Supplier'
SELECT p.product_name AS Product, 
       s.supplier_name AS Supplier
-- From the Products table aliased as 'p'
FROM Products p
-- Join with the subquery result aliased as 's'
JOIN (
    -- Select supplier_id and supplier_name from Suppliers table where the city is 'New York'
    SELECT supplier_id, 
           supplier_name
    FROM Suppliers
    WHERE city = 'New York'
) AS s 
-- On matching supplier_id between Products and the subquery result
ON p.supplier_id = s.supplier_id;