当使用COUNT和WHERE时，如何计算每年总数的百分比?

Question

在SQL Server中，我有一个查询

SELECT season, COUNT(DISTINCT player_name) AS 'No. of Foreign Players'
FROM nbastats
WHERE country <> 'USA'
GROUP BY season

它返回这些结果

<表类>id季节。tbody><<tr>11996 - 97921997 - 981431998 - 992241999 - 002452000 - 01年4062001 - 02年5172002 - 03年62

我想你需要一个条件比率:

SELECT season,
COUNT(DISTINCT CASE WHEN country <> 'USA' THEN player_name END) * 1.0 / COUNT(DISTINCT player_name) AS foreign_ratio
FROM nbastats
GROUP BY season