That's right! Aliases are also convenient in other situations. Let's analyze the following situation:
We want to put information about children and their mothers into a database. At some point, we would also like to show children together with their mothers using a join.
Let's say we store both children and mothers in the same table
person which has a column
mother_id. This column contains the id of the person who has the mother and this id is taken from the very same table person.
The question is: can we join the table
person with the table
person? The answer is simple: yes, we can! You can't write
person JOIN person
in your SQL query, but you can provide two different aliases for the same table:
FROM person AS p1
JOIN person AS p2
ON p1.id = p2.mother_id;
Thanks to the aliases, the database engine will use the same table person twice – the first time to look for children and the second time to look for their mothers.