在Postgres表中獲取列中最常用的一週

Question

我想查看一下我的Postgres數據庫上的小部件獲得created_at的一週中最常見的一天。

這是盡我所能，但它返回我平均（3.744 ...），而不是一個整數代表最常見的星期幾。有誰知道我可以如何改善這一點？

SELECT AVG(start_day) AS start_day 
FROM (SELECT date_part('dow', created_at) AS start_day 
     FROM widgets) TMP; 

Answer 1

SELECT date_part('dow', created_at) AS start_day 
    FROM widgets 
GROUP BY date_part('dow', created_at) 
ORDER BY COUNT(*) DESC 
LIMIT 1 

Answer 2

SELECT start_day, count(*) 
FROM (
    SELECT date_part('dow', created_at) AS start_day 
    FROM widgets) sub 
GROUP BY 1 
ORDER BY 2 DESC 
LIMIT 1;