How to create virtual column using MySQL SELECT?

Question

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 quer

Answer 1

You could use a CASE statement, like

SELECT name
       ,address
       ,CASE WHEN a < b THEN '1' 
             ELSE '2' END AS one_or_two
FROM ...