如何按范围 select 行？

Question

我有以下 table 名为 'T'

我想要的输出应该如下所示，

我想要 select 列 'Actual' 的那些行的范围应该在列 'Basic'[=35 之间=]，但是，如果您以 'Model' = HT65 为例 'Actual' = 23.2 的范围在列 'Basic' 的 22 和 24 之间，所以我应该得到行如下列'Level' 是 2

同样，其他行也应 selected。您的帮助将不胜感激。

Answer 1

您可以使用以下解决方案，使用多个 LEFT JOIN 来连接当前行的下一行和最后一行。在一些附加条件下，您可以检查范围：

SELECT t1.Model, t1.Level, t1.Basic, t1.Actual
FROM (
  SELECT *, ROW_NUMBER() OVER (PARTITION BY Model ORDER BY Basic) AS rn 
  FROM test
) t1 LEFT JOIN (
  SELECT *, ROW_NUMBER() OVER (PARTITION BY Model ORDER BY Basic) AS rn 
  FROM test
) t2 ON t1.Model = t2.Model AND t1.rn + 1 = t2.rn LEFT JOIN (
  SELECT *, ROW_NUMBER() OVER (PARTITION BY Model ORDER BY Basic) AS rn 
  FROM test
) t3 ON t1.Model = t3.Model AND t1.rn - 1 = t3.rn
WHERE (t1.Actual BETWEEN t3.Basic AND t1.Basic)
  OR (t3.Model IS NULL AND t1.Actual < t1.Basic)
  OR (t2.Model IS NULL AND t1.Actual > t1.Basic)
ORDER BY t1.Model ASC

以上查询获取了所有预期的行。我还添加了一些额外的案例来改进对这些（特殊）案例的查询。上述解决方案适用于 SQL-Server 2008.

自 SQL-Server 2012 年起，您可以通过 LAG and LEAD 使用以下解决方案：

SELECT t.Model, t.Level, t.Basic, t.Actual
FROM (
  SELECT *, LAG(Basic, 1,0) OVER (PARTITION BY Model ORDER BY Basic) AS prevBasic,
    LEAD(Basic, 1, 0) OVER (PARTITION BY Model ORDER BY Basic) AS nextBasic
  FROM test 
) t 
WHERE (t.Actual BETWEEN t.prevBasic AND t.Basic)
   OR (t.nextBasic = 0 AND t.Actual > t.Basic)
ORDER BY t.Model ASC

demo on dbfiddle.uk

如何按范围 select 行？

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