Question

I want to execute a SQL query in mysql something like the below:

SELECT
(0-5) AS `sqlTest`, if(`sqlTest` < 0, 'false', 'true')

But I am getting an error “Unknown column ‘sqlTest’ in ‘field list'”

Note

This is not an exact query. Here the operands 0 and 5 will be replaced
with 2 big Select queries.

Answer 1

Since you’re using MySQL, you can use a temporary to solve it;

SELECT @tmp := (0-5) AS `sqlTest`, if(@tmp < 0, 'false', 'true')

Simple demo here.