如何过滤NTILE window函数？

Question

以下是我尝试查看投球局数排名前 98% 的投手。我正在尝试过滤 NTILE() window 函数，但它抛出错误。

 query = """ 

WITH pitching_cte AS 
(
SELECT
player,
player_id,
season,
CAST(strftime('%Y', birth_date) AS TEXT) AS birth_year,
COUNT(*) AS num_seasons, 
printf("%i.%i", outs/3, outs % 3) AS innings_pitched
FROM pitching
INNER JOIN player
USING(player_id)
GROUP BY player
)

SELECT innings_pitched, 
   birth_year, 
   player, 
   NTILE(100) OVER(PARTITION BY innings_pitched) pctl,
   num_seasons
FROM pitching_cte
WHERE season = 2021 AND pctl >= 98;

"""
df = pd.read_sql(query, cnxn)
print(df.head(10))

当我执行此查询时，出现以下错误：

DatabaseError: Execution failed on sql ' 

WITH pitching_cte AS 
(
 SELECT
player,
player_id,
season,
CAST(strftime('%Y', birth_date) AS TEXT) AS birth_year,
COUNT(*) AS num_seasons, 
printf("%i.%i", outs/3, outs % 3) AS innings_pitched
FROM pitching
INNER JOIN player
USING(player_id)
GROUP BY player)

 SELECT innings_pitched, 
   birth_year, 
   player, 
   NTILE(100) OVER(PARTITION BY innings_pitched) pctl,
   num_seasons
FROM pitching_cte
WHERE season = 2021 AND pctl >= 98;

': misuse of aliased window function pctl

如何过滤生成的百分位数列？

谢谢

Answer 1

通常无法在 WHERE 子句中使用 SELECT 列表中定义的别名。

另一个限制是窗口函数不能在 WHERE 子句中使用，所以下面的语句也会失败：

SELECT innings_pitched, 
   birth_year, 
   player, 
   NTILE(100) OVER(PARTITION BY innings_pitched) pctl,
   num_seasons
FROM pitching_cte
WHERE season = 2021 AND (NTILE(100) OVER(PARTITION BY innings_pitched)) >= 98;

解决方案是使用另一层cte：

WITH pitching_cte AS (
  SELECT
    player,
    player_id,
    season,
    CAST(strftime('%Y', birth_date) AS TEXT) AS birth_year,
    COUNT(*) AS num_seasons, 
    printf("%i.%i", outs/3, outs % 3) AS innings_pitched
  FROM pitching
  INNER JOIN player
  USING(player_id)
  GROUP BY player
), cte AS (
  SELECT innings_pitched, 
    birth_year, 
    player, 
    NTILE(100) OVER(PARTITION BY innings_pitched) pctl,
    num_seasons
  FROM pitching_cte
  WHERE season = 2021
)
SELECT *
FROM cte
WHERE pctl >= 98;

相关：Why no windowed functions in where clauses?

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