Альберт

query = String.Format("declare" +
         " a int;" +
         " BEGIN" +
         " SELECT count(city.city_id) into a FROM city WHERE city.name = '{0}';" +
         " if a = 0 THEN" +
         " insert into city(CITY_ID, NAME) values(supplier_seq.NEXTVAL, '{0}');" +
         " end if;" +
         " SELECT city.city_id into a FROM city WHERE city.city_id =(select min(city.city_id) from city where city.name = '{0}');" +
         " INSERT INTO FIRM(FIRM_ID, NAME, JUR_CITY_ID) VALUES(supplier_seq.NEXTVAL, '{2}', a);" +
         " COMMIT;" +
         " end; ", JUR_CITY, POST_CITY, NAME);