testing select from boolean columns in firebird 3.0 http://asfernandes.blogspot.com/2010/12/introducing-boolean-datatype.html

select from boolean columns.sql

Check what values we have

SQL> SELECT * from true_values;

COLUMN_ONE COLUMN_TWO 
========== ========== 
<false>    <false>    
<true>     <false>    
<true>     <false>    
<false>    <true>     
<false>    <true>     
<true>     <true>     

--Check the disjunction (Logical or )
--http://en.wikipedia.org/wiki/Truth_table#Logical_disjunction

SQL> SELECT column_one or column_two from true_values;

        
======= 
<false> 
<true>  
<true>  
<true>  
<true>  
<true>  


--Check the conjunction (Logical and)
--http://en.wikipedia.org/wiki/Truth_table#Logical_conjunction

SQL> SELECT column_one and column_two from true_values;

        
======= 
<false> 
<false> 
<false> 
<false> 
<false> 
<true>  
--Check the negation 
--
SQL> select not(column_one) from true_values;

Creating a “truth table” is not hard, you can use an useful tool (CKod, at http://ckod.sourceforge.net/_/) to make a “truth table”.

1. CKod homepage: http://ckod.sourceforge.net/
2. CKod online: http://ckod.sourceforge.net/_/
3. CKod forum: http://ckod.sourceforge.net/~/

Good luck to you!