如何編寫一個查詢來獲取mysql中的計數

Question

我想獲得今天的用戶數和昨天的用戶數量，我想只寫一個查詢我該怎么做...？

這些是我的查詢我只想要一個查詢：

SELECT COUNT(*) FROM visitors group by visited_date ORDER by visited_date DESC limit 1,1 as todayCount

SELECT COUNT(*) FROM visitors group by visited_date ORDER by visited_date DESC limit 1,0 as yesterdayCount

我的預期結果還是只有2列

todayCount yesterdayCount
     2          4

Answer 1

這應該做的伎倆：

SELECT COUNT(CASE 
                WHEN visited_date = CURDATE() THEN 1 
             END) AS todayCount ,
       COUNT(CASE 
                WHEN visited_date = CURDATE() - INTERVAL 1 DAY THEN 1 
             END) AS yesterdayCount 
FROM visitors  
WHERE visited_date IN (CURDATE(), CURDATE() - INTERVAL 1 DAY)
GROUP BY visited_date
ORDER by visited_date 

Answer 2

如果你知道當前和以前的日期，那么你可以這樣做：

SELECT SUM(visited_date = CURDATE()) as today,
       SUM(visited_date = CURDATE() - interval 1 day) as yesterday
FROM visitors
WHERE visited_date >= CURDATE() - interval 1 day;

如果您不知道這兩天，那么您可以做類似的事情，獲取數據中的最新日期：

SELECT SUM(v.visited_date = m.max_vd) as today,
       SUM(v.visited_date < m.max_vd) as yesterday
FROM visitors v CROSS JOIN
     (SELECT MAX(v2.visited_date) as max_vd FROM visitors v2) as m
WHERE v.visited_date >= m.max_vd - interval 1 day

Answer 3

試試這個簡單的查詢

select visited_date as date, COUNT(*) as count from `visitors` 
group by `visited_date` order by `visited_date` asc

它會產生輸出

它會對你有用。

Answer 4

試試這個：$ sqlToday =“選擇COUNT（*）FROM menjava WHERE DATE（date_submitted）= CURRENT_DATE（）”;

$ sqlY yesterday =“選擇COUNT（*）FROM menjava WHERE DATE（dc_created）= CURDATE（） - INTERVAL 1 DAY”;