SET TERM #;
execute block
as
begin
    if (exists(
    select 1 from RDB$RELATION_FIELDS rf
    where rf.RDB$RELATION_NAME = 'TABLE1' and rf.RDB$FIELD_NAME = 'FIELD1'/*тут еще хочу добавить условие на тип не varchar на поле FIELD1*/))
    then
        execute statement 'ALTER TABLE TABLE1 alter column FIELD1 type varchar(40)';
	execute statement 'update TABLE1 set FIELD1=trim (trailing ''.'' from (trim (trailing ''0'' from FIELD1)))';		
end #
SET TERM ;#

SET TERM #;
execute block
as
begin
    if (exists(
    select 1 from RDB$RELATION_FIELDS rf
    where rf.RDB$RELATION_NAME = 'TABLE1' and rf.RDB$FIELD_NAME = 'FIELD1'/*добавить условие на тип НЕ варчар*/))
    then
	begin
                execute statement 'ALTER TABLE TABLE1 alter column FIELD1 type varchar(40)';	
	END
	ELSE
	BEGIN
		execute statement 'update TABLE1 set FIELD1=trim (trailing ''.'' from (trim (trailing ''0'' from FIELD1)))';		
	end
end #
SET TERM ;#