ROW_NUMBER（）在SQL中没有结束

Question

有什么方法可以在SQL中使用ROW_NUMBER()而不使用OVER，因为我想使用排序。

我有一个网格，其中有多个可排序的列以及可配置的行。在我的方案中，order by是变量，这就是为什么我无法使用ROWNUM下订单的原因。

Answer 1

select ROW_NUMBER() OVER (ORDER BY (SELECT NULL)) as number from Task order by RuleId

Answer 2

我使用不同的逻辑来解决这个问题。而不是检查每一天并确认它是工作日还是假日，我创建一个表，该表仅列出工作日，然后采用第n个值。

CREATE OR REPLACE FUNCTION add_n_working_days ( 
  start_date DATE, working_days PLS_INTEGER
) RETURN DATE AS
  l_end_date DATE := start_date;
  l_counter  pls_integer := 0;
BEGIN
  SELECT 
    business_day 
    INTO l_end_date
  FROM 
  (
    WITH 
    dates AS
      (SELECT start_date + level - 1  as dt FROM dual CONNECT BY level < 100)
    ,weekdates AS
    (SELECT dt as weekday FROM dates WHERE TO_CHAR(dt,'fmdy') NOT IN ('sat','sun'))
    ,business_days AS
    (
    SELECT weekday as business_day FROM weekdates
    MINUS
    SELECT holiday FROM so_holidays 
    )
    SELECT business_day, ROW_NUMBER() OVER (ORDER BY 1) as rn from business_days
  )
  WHERE rn = working_days + 1;
  RETURN l_end_date;
END add_n_working_days;

如果working_days太高，那么我建议将其设置为变量。