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Aliases

SQL aliases are used to give a table, or a column in a table, a temporary name.

Aliases are often used to make column names more readable.

An alias only exists for the duration of that query.

An alias is created with the AS keyword.

Example

Using aliases for columns:

SELECT customer_id AS id
FROM customers;

AS is Optional

Actually, you can skip the AS keyword and get the same result:

Example

Same result without AS:

SELECT customer_id id
FROM customers;

Concatenate Columns

The AS keyword is often used when two or more fields are concatenated into one.

To concatenate two fields use ||.

Example

Concatenate two fields and call them product:

SELECT product_name || unit AS product
FROM products;

Note: In the result of the example above we are missing a space between product_name and unit. To add a space when concatenating, use || ' ' ||.

Example

Concatenate, with space:

SELECT product_name || ' ' || unit AS product
FROM products;

Using Aliases With a Space Character

If you want your alias to contain one or more spaces, like "My Great Products", surround your alias with double quotes.

Example

Surround your alias with double quotes:

SELECT product_name AS "My Great Products"
FROM products;

PostgreSQL Exercises

Test Yourself With Exercises

Exercise:

Make an alias for the field customer_name so that it will be dispalyed as Company:

SELECT customer_name  FROM customers;

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