Subject Why field alias can not be used in where clause?
Author Glebas

Using FB1.52 on Windows:

select tbl.fld as alias from tbl where alias is null

complains about 'alias' in 'where' clause:
'Column does not belong to referenced table'

in firebird 2 release notes I found that now field aliases can be used
in 'order by' and 'group by'. But why 'where' clause is so special?