create collation PXW_CYRL_CI_AI for WIN1251
   from PXW_CYRL
   CASE INSENSITIVE
   ACCENT INSENSITIVE;

with A(val) as(
  select cast('update' as blob sub_type text) from rdb$database
  union all
  select 'UPDATE' from rdb$database
)
select * from A where val collate PXW_CYRL_CI_AI like '%update%'