Does GORM has issue with field starts with max prefix or issue with Float field

Question

i have a domain class that contains two fields : minscale, and maxscale :

class TeamRuleAverageStatic extends TeamRule {
    Float minscale; 
    Float maxscale;

}

* i persist a record in database with minscale=0.5 and maxscale=0.9

And when i tried to query it , i don't get anything :

TeamRuleAverageStatic.findByMinscaleAndMaxscale(new Float(0.5),new Float(0.9));

I make another attempt , but without embedding maxscale :

 TeamRuleAverageStatic.findByMinscale(new Float(0.5));

So i get the expected result .

i try also :

     TeamRule.executeQuery('from TeamRule cu where cu.maxscale = ? and cu.minscale= ?', [new Float(0.9),new Float(0.5)])
// As TeamRule is the class mother of TeamRuleAverageStatic

Issue persists yet . it seems that MAXSCALE is a keyword or fields that start with the prefix 'max' , because query by the MINSCALE field works perfectly

UPDATE:

i do best practices with SQL query manually using phphmyadmin as GUI,

i get the same problem .

When i change the type of field to Double it works ! WEIRD

Reallly, it is the strange IT issue that meets me . What is the problem with FLOAT type ?

Answer 1

Your issue is cause by the nature of representation float and double values. Both are used to represent floating point numbers, where float is for single-precision and double is for double-precision numbers.

MySQL uses four bytes for single-precision values and eight bytes for double-precision values.

As from the MySql manual:

Because floating-point values are approximate and not stored as exact values, attempts to treat them as exact in comparisons may lead to problems.

You could try to use decimal instead of float or double because decimal is represented as strings internally to guarantee an exact precision.