Question

我可以通过计算行，通过row_number() OVER()对结果进行编号吗？

e.g。

SELECT *,
    users::numeric/population::numeric*100 AS penetration,
    row_number() OVER(ORDER BY penetration DESC)
FROM states ORDER BY penetration DESC

生成错误：

ERROR: column "penetration" does not exist

Answer 1

我不使用postgre但是对于t-sql你必须做这样的事情：

SELECT *,
    penetration,
    row_number() OVER(ORDER BY penetration DESC)
FROM 
(
   select users::numeric/population::numeric*100 AS penetration
   from states
)pen
 ORDER BY penetration DESC

Answer 2

你不能在postgresql中这样做。在这里查找expression：4.2.8. Window Function Calls，它说 ..它不能是输出列名称或数字..

您可以使用子查询：

SELECT states.*, penetration, row_number() OVER(ORDER BY penetration DESC)
  FROM states
  JOIN (SELECT id, users::numeric/population::numeric*100 AS penetration
          FROM states) s_pen on spen.id = states.id
 ORDER BY s_pen.penetration DESC

在OVER（）子句中使用别名

2 个答案: