update generators values ​​according to the primary key field.

update_value_generators.sql

execute block
as
    declare variable trigger_name varchar(32);
    declare variable table_name varchar(32);
    declare variable generator_name varchar(32);
    declare variable last_id integer;
    declare variable sql varchar(100);
    declare variable pk_field_name varchar(32);
begin
    for
        select
            t.rdb$trigger_name,
            t.rdb$relation_name,
            d.rdb$depended_on_name
        from
            rdb$triggers t
            inner join rdb$dependencies d on (d.rdb$dependent_name = t.rdb$trigger_name and d.rdb$depended_on_type = 14)
        where
            t.rdb$system_flag = 0
        order by
            t.rdb$trigger_name
        into
            :trigger_name,
            :table_name,
            :generator_name
    do begin
        select distinct
            s.rdb$field_name
        from
            rdb$indices i
        left join rdb$index_segments s on i.rdb$index_name = s.rdb$index_name
        left join rdb$relation_constraints rc on rc.rdb$index_name = i.rdb$index_name
        left join rdb$dependencies d on d.rdb$depended_on_name = rc.rdb$relation_name
        where
            rc.rdb$constraint_type = 'PRIMARY KEY'
            and d.rdb$dependent_name = :trigger_name
        into
            :pk_field_name;    

        sql = 'SELECT COALESCE(MAX(' || :pk_field_name || '), 0) FROM ' || :table_name;
        execute statement :sql into :last_id;

        -- update generator's value
        sql = 'ALTER SEQUENCE ' || :generator_name || ' RESTART WITH ' || (:last_id) || ';';
        execute statement :sql;
        suspend;
    end
end