I want to do some arithmetic in query using temporary field.
SELECT point, '5' AS bonus, (bonus*2) AS total FROM arithmetic
but the temp field is unknown
Unknown column 'bonus' in 'field list'
how can i use or called temp field in query?
You can either use a user variable here to store the valus of bonus, or use a subquery/CTE. Assuming the latter, and that you are running MySQL 8+, we can try:
WITH cte AS ( SELECT point, 5 AS bonus FROM arithmetic ) SELECT point, bonus, 2*bonus AS total FROM cte;