关键是生成一系列工作日，并用
row_number()以下编号对它们进行编号：
create or replace function add_business_day(from_date date, num_days int)returns dateas $fbd$ select d from ( select d::date, row_number() over (order by d) from generate_series(from_date+ 1, from_date+ num_days* 2+ 5, '1d') d where extract('dow' from d) not in (0, 6) and d not in (select pyha from pyha) ) s where row_number = num_days$fbd$ language sql;测试查询的结果似乎正确：
select days, add_business_day('2018-12-08', days)from generate_series(1, 20) days days | add_business_day ------+------------------ 1 | 2018-12-10 2 | 2018-12-11 3 | 2018-12-12 4 | 2018-12-13 5 | 2018-12-14 6 | 2018-12-17 7 | 2018-12-18 8 | 2018-12-19 9 | 2018-12-20 10 | 2018-12-21 11 | 2018-12-27 12 | 2018-12-28 13 | 2018-12-31 14 | 2019-01-02 15 | 2019-01-03 16 | 2019-01-04 17 | 2019-01-07 18 | 2019-01-08 19 | 2019-01-09 20 | 2019-01-10(20 rows)或者，您可以在循环中找到日期：
create or replace function add_business_day_loop(from_date date, num_days int)returns dateas $fbd$begin while num_days > 0 loop from_date:= from_date+ 1; while from_date in (select pyha from pyha) or extract('dow' from from_date) in (0, 6) loop from_date:= from_date+ 1; end loop; num_days:= num_days- 1; end loop; return from_date;end;$fbd$ language plpgsql;
