php - Why is there a problem with sql calculation results! ! ! !

Question

Why are the highest and lowest values ​​reversed? Some are normal and some are abnormal. Is this written wrong?

These two are executed by the front and rear feet, what's the problem! ! !

Answer 1

Is your yj a numeric type? It feels like a string type.

Answer 2

Because your yj field may be of string type

Answer 3

The person above is right, yours has been sorted according to ASCII code, which is definitely wrong