ORA-00904: "PREV_TEMP": 具有 LAG 函数的无效标识符

Question

这个查询有什么问题？

它returns： ORA-00904: "PREV_TEMP": invalid identifier

SELECT Id, RecordDate, Temperature, LAG(Temperature) OVER (ORDER BY RecordDate) as prev_temp
FROM Weather
WHERE Temperature > prev_temp;

SQL 架构：

Create table If Not Exists Weather (Id int, RecordDate date, Temperature int)
Truncate table Weather
insert into Weather (Id, RecordDate, Temperature) values ('1', '2015-01-01', '10')
insert into Weather (Id, RecordDate, Temperature) values ('2', '2015-01-02', '25')
insert into Weather (Id, RecordDate, Temperature) values ('3', '2015-01-03', '20')
insert into Weather (Id, RecordDate, Temperature) values ('4', '2015-01-04', '30')

Answer 1

不能直接使用，需要在子查询中使用才能使用解析函数的返回值

SELECT *
  FROM
  (
   SELECT Id, RecordDate, Temperature, 
          LAG(Temperature) OVER (ORDER BY RecordDate) as prev_temp
     FROM Weather
  )
  WHERE Temperature > prev_temp;

Answer 2

查询的错误在于，列别名不能是 SELECT、WHERE、FROM 或 GROUP BY 子句中的 re-used，其中他们被定义。这适用于 window 功能，以及其他一切。而这是SQL中的规则，而不是Oracle中的规则（虽然有些数据库放宽了对GROUP BY的限制）。 =16=]

对于您的情况，基本上有两种解决方案，子查询和 CTE：

WITH w AS (
      SELECT w.*,
             LAG(Temperature) OVER (ORDER BY RecordDate) as prev_temperature
      FROM weather w
     ) 
SELECT Id, RecordDate, Temperature,  prev_temp
FROM w
WHERE Temperature > prev_temp;

ORA-00904: "PREV_TEMP": 具有 LAG 函数的无效标识符

ORA-00904: "PREV_TEMP": invalid identifier with LAG function

sql

oracle

analytic-functions