How do emulate INSERT IGNORE of MySQL?
MySQL has INSERT IGNORE construct that tries to insert the record, and if record with such primary key already exists, the error is ignored. This is mostly useful when inserting multiple rows at once, but you might want to use it for single row as well.
The closest equivalent is to use EXECUTE BLOCK and ignore the duplicate key error (-803):
execute block as begin
INSERT INTO ... VALUES (...);
when SQLCODE -803 do exit; end