Question

我有一个包含以下各列的销售表。我想选择销售价格正在增加的行，而跳过那些降低价格的行，其中上一行的销售价格正在增加。例如在下表中，我希望除具有saleid=4

的行之外的所有行

+--------+--------+-----------+
| SaleId | ItemId | SalePrice |
+--------+--------+-----------+
| 1      | 987    | 12        |
+--------+--------+-----------+
| 2      | 678    | 13        |
+--------+--------+-----------+
| 3      | 987    | 15        |
+--------+--------+-----------+
| 4      | 542    | 11        |
+--------+--------+-----------+
| 5      | 678    | 16        |
+--------+--------+-----------+

我尝试使用内部联接。但是它什么也没显示。这是我写的查询：

select s1.* from saletable s1
join saletable s2 on s1.saleid = s2.saleid
where s1.saleprice<s2.saleprice

Answer 1

使用运行max来考虑以下解决方案

select t.*
from
(
    select *, max(SalePrice) over (order by SaleId) runningMaxSalePrice
    from testdata
) t
where t.SalePrice >= t.runningMaxSalePrice

此解决方案跳过了多个连续的行，并降低了SalePrice。

DBFdiddle DEMO

Answer 2

使用lag()：

select st.*
from (select st.*, lag(saleprice) over (order by saleid ) as prev_saleprice
      from saletable st
     ) st
where prev_saleprice is null or saleprice > prev_saleprice

比较上一列数据和下一列数据

2 个答案: