比较SQL查询中的两个日期

Question

我有一个表roomtype ，其中包含以下数据：

Hotel_ID    Name     Rate   Season    StartSeason   EndSeason
   1      Deluxe/Ac  2700   New Year  2013-12-20    2014-01-10
   1      Deluxe/Ac  3100   31 Dec    2013-12-31    2012-12-31
   1      Deluxe/Ac  1700   Diwali    2013-11-01    2013-11-15
   1      Deluxe/Ac  800    Normal    NULL          NULL

对于给定的日期（即2013-11-09 ），我想返回匹配季节的rate ，其中给定的日期在StartSeason和EndSeason日期之内。

即，如果我的日期是2013-11-09 ，那么比率应该是1700。如果我的日期是2012-09-09 ，那么比率应该是800。

如何创建存储过程或编写SQL查询？

Answer 1

select top 1 hotel_id, rate
from roomtype r
where '2013-11-09' between startseason and endseason
or startseason is null and endseason is null
order by case when startseason is null and endseason is null then 2 else 1 end

Answer 2

为了改善查询优化器的辛苦工作，您可以帮助他在子查询中使用UNION ALL运算符

SELECT TOP 1 *
FROM (SELECT TOP 1 *
      FROM Table1
      WHERE @date BETWEEN StartSeason AND EndSeason
      UNION ALL
      SELECT TOP 1 *
      FROM Table1
      WHERE StartSeason IS NULL
      ) x
ORDER BY StartSeason DESC

当然，除了此查询外，提供正确的索引也将是非常不错的

CREATE INDEX x ON Table1(StartSeason)
  INCLUDE(EndSeason,Hotel_ID,Name,Rate,Season)

平面图

参见有关SQLFiddle演示

Answer 3

这应该为您提供查询中日期与季节匹配的汇率：

SELECT rate FROM roomtype 
   WHERE StartSeason >= '2013-11-09' AND EndSeason <= '2013-11-09';