连续获得最小值答案

【问题标题】：Get Least Value in a row连续获得最小值
【发布时间】：2021-06-08 00:41:46
【问题描述】：

我有如下 12 个月的条目，我想获得它的最小值。我有一个想法用CASE 表达式来实现，但它的可读性看起来太复杂了。

表格

   +----------------------------------------------------------------------------+
   | Id | Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec |
   +----------------------------------------------------------------------------+
   | 1  | 0.1 | 1   | -2  | -0.5|  3  |  5  |  9  | 1.5 | 2.5 | 3.6 | 3.6 | 2.5 |
   | 2  | 3   | 2   | 5   | 2.5 |  3  |  6  |  10 | 1.1 | 2.8 | 2.6 | 5.6 | 1.8 |
   | 3  | -1  | 1   | 3   | -0.5|  3  |  5  |  9  | 1.5 | 2.5 | 3.6 | 3.6 | 2.5 |
   +----------------------------------------------------------------------------+

预期输出

   +------------------------------------------------------------------------------------+
   | Id | Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | Least |
   +------------------------------------------------------------------------------------+
   | 1  | 0.1 | 1   | -2  | -0.5|  3  |  5  |  9  | 1.5 | 2.5 | 3.6 | 3.6 | 2.5 | -2    |
   | 2  | 3   | 2   | 5   | 2.5 |  3  |  6  |  10 | 1.1 | 2.8 | 2.6 | 5.6 | 1.8 | 1.1   |
   | 3  | -1  | 1   | 3   | -0.5|  3  |  5  |  9  | 1.5 | 2.5 | 3.6 | 3.6 | 2.5 | -1    |
   +------------------------------------------------------------------------------------+

我尝试过如下查询，但它的可读性太复杂 - 有什么方法可以更有效地做到这一点？

SELECT Id, Jan, Feb, Mar, Apr, May, Jun, Jul, Aug, Sep, Oct, Nov, Dec,
       CASE WHEN Jan< Feb && Jan < Mar && Jan < Apr && Jan < MAY && Jan < Jun && Jan < Jul && Jan < Aug && Jan < Sep && Jan < Oct && Jan < Nov && Jan < Dec THEN Jan
            WHEN Feb < Jan && Feb < Mar && Feb < Apr && Feb < MAY && Feb < Jun && Feb < Jul && Feb < Aug && Feb < Sep && Feb < Oct && Feb < Nov && Feb < Dec THEN Feb
            WHEN...
       END AS Least     
FROM table

【问题讨论】：

标签： sql sql-server tsql min

【解决方案1】：

你可以试试cross apply。见下面的脚本：

SELECT Id, Jan, Feb, Mar, Apr, May, Jun, Jul ,Aug, Sep, Oct, Nov, Dec, Least
FROM Test
CROSS APPLY (SELECT MIN(MinColVal) AS Least FROM (VALUES (Jan),(Feb),(Mar),(Apr),(May),(Jun),(Jul),(Aug),(Sep),(Oct),(Nov),(Dec)) AS a(MinColVal))tab

【讨论】：

@VigneshKumarA 。 . .你应该接受这个答案。

【解决方案2】：

这应该可以解决问题。

SELECT ID, MIN(MONTH) AS Least
FROM
(
    SELECT JAN AS MONTH
    FROM ##table
    UNION ALL
    SELECT FEB AS MONTH
    FROM ##table
    UNION ALL
    SELECT MAR AS MONTH
    FROM ##table
) mon
GROUP BY ID

【讨论】：