sql - 你能帮我找到我似乎无法转换为整数吗？

Question

我要做的就是Scan从每个''中提取最新的''（因此是'LastScan'）location，然后找出它们中的任何一个是否超过2小时或更多' old'（这会使它们过期）。

Select cast(max(entered_date) as int) as 'LastScan', location
FROM housing_activity
WHERE 'LastScan' <= Datediff(HH,-2,GETDATE())
Group by location

这是我的错误：

Msg 245, Level 16, State 1, Line 2
Conversion failed when converting the varchar value 'LastScan' to data type int.

Answer 1

尝试这个

; WITH cte AS (
SELECT
  location
  , LastScan = entered_date
  , RN = ROW_NUMBER() OVER (PARTITION BY location ORDER BY entered_date DESC)
FROM housing_activity 
)
SELECT 
  *
FROM cte
WHERE 
   RN = 1
   AND LastScan <= DateAdd(hour,-2,GETDATE())