As I answer you on your first time question - use this query to get next ID. Then supply this ID in your next INSERT query.
select gen_id(GEN_TABLENAME, 1) from RDB$DATABASE Where GEN_TABLENAME - generator for your A.ID column. In this case you not need to declare you column as IDENTITY. Instead create GENERATOR and BEFORE INSERT trigger like this: CREATE GENERATOR GEN_TABLENAME; SET TERM ^ ; CREATE OR ALTER TRIGGER TABLENAME_BI FOR TABLENAME ACTIVE BEFORE INSERT POSITION 0 AS begin if (new.ID is null) then new.ID = gen_id(GEN_TABLENAME, 1); end ^ SET TERM ; ^
