If I do SELECT a AS b and b is not a column in the table, would query create the "virtual" column?
in fact, I need to incorporate some virtual column into the query and process some information into the query so I can use it with each item later on.
SELECT id, email, IF(actived = 1, 'enabled', 'disabled') AS account_status FROM users
this allow you to make operations and show it as columns.
you can also use joins and show operaitons as columns:
SELECT u.id, e.email, IF(c.id IS NULL, 'no selected', c.name) as country FROM users u LEFT JOIN countries c ON u.country_id = c.id
Try this one if you want to create a virtual column "age" within a select statement:
select brand, name, "10" as age from cars...