选择最接近的匹配答案

【问题标题】：Select closest match选择最接近的匹配
【发布时间】：2017-07-26 04:58:53
【问题描述】：

我正在尝试合并两个表（pc 和 mc），但下面的语句可能会从 mc 中产生多条记录。我希望查询只返回 mc 中的匹配，其中 cast(pc.ten as date) - cast(mc.to as date) 为正但尽可能小。我怎么做？

CREATE TABLE test AS SELECT DISTINCT pc.number, mc.number
FROM pc
INNER JOIN mc
ON pc.member = mc.member AND pc.ned = mc.ned AND cast(pc.ten as date) BETWEEN cast(mc.to as date) + 1 AND cast(mc.to as date) + 11 AND
pc.ned IS NOT NULL AND mc.ned IS NOT NULL;

【问题讨论】：

标签： sql postgresql inner-join

【解决方案1】：

CREATE OR REPLACE VIEW test AS 

  SELECT n1, n2 
  FROM (
    SELECT 
      pc.number as n1, 
      mc.number as n2, 
      ROW_NUMBER() OVER (ORDER BY cast(pc.ten as date) - cast(mc.to as date) ASC) AS Rank
    FROM pc
    INNER JOIN mc ON pc.member = mc.member AND pc.ned = mc.ned 
    WHERE cast(pc.ten as date) - cast(mc.to as date) > 0
  ) 
  WHERE Rank = 1

【讨论】：