Filip wrote: 

> I like to understand then why a1.value=chr(78493) performs better than
> num(a1.value)=78493? 

chr(78493) is a constant value and every a1.value can be compared with this without 
any conversion.

num(a1.value) has to be calculated for every row before comparison. As you can 
imagine, this is more work and the optimizer cannot draw any assumptions on value from 
the statistics.

> Then I can judge the right way of writing for other queries too.

HTH
Christian
-- 
#include <std_disclaimer.h>
/* The opinions stated above are my own and not
   necessarily those of my employer. */


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