Postgres：子查詢中時間戳的日期分組

Question

我正在嘗試找出每天每個列表產生多少線索。

我有這個查詢：

SELECT 
    vl.listing_id,
    vl.created_at::date as dt,
    (
        SELECT count(*) 
        FROM voice_leads vl2
        WHERE vl2.listing_id = vl.listing_id 
        AND vl.created_at::date = vl2.created_at::date
    ) as cnt
FROM voice_leads vl
GROUP BY listing_id, vl.created_at::date
ORDER BY listing_id

但是執行時出現“錯誤：子查詢從外部查詢第8行使用未分組的列“ vl.created_at”：AND vl.created_at :: date = vl2.created_at :: date”

關於如何解決該問題的任何想法？

Answer 1

SELECT 
    vl.listing_id,
    vl.created_at::date as dt,
    count(cnt.*)
FROM voice_leads vl, lateral (SELECT *
        from voice_leads vl2
        WHERE vl2.listing_id = vl.listing_id 
        AND vl.created_at::date = vl2.created_at::date) cnt
GROUP BY vl.listing_id, vl.created_at::date
ORDER BY listing_id

Answer 2

您不需要子查詢：

SELECT 
    vl.listing_id,
    vl.created_at::date as dt,
    count( vl.listing_id ) as cnt
FROM voice_leads vl
GROUP BY listing_id, vl.created_at::date
ORDER BY listing_id

應該做的一樣。

count(field)將計算每個組中的行數。

count(*)將計算總行數。