如何在MYSQL select查询中进行多次计数？

我有下面的查询，我想在一行中得到这些查询返回的结果。 如下图所示：

SELECT count(item_id) as today FROM table1 
WHERE DATE(creation_date) > DATE(NOW() - INTERVAL 1 DAY);

SELECT count(item_id) as yesterday from table1
where DATE(creation_date) = DATE(NOW() - INTERVAL 1 DAY);

SELECT count(item_id) year_period from table1
where creation_date > now() - interval 1 year;

我有一些方法来实现这一点，但我想一个更有效的解决方案，以实现我想要的。 我可以通过这里看到的工会来实现我想要的

----------------------------------------
|today |  yesterday  | one_year_period |
----------------------------------------
|   2  |    5        |        7        |
----------------------------------------

我想优化我的解决方案，使查询不会在3个不同的场合重复。

使用CASE语句：

SELECT count(item_id) as today FROM table1 
WHERE DATE(creation_date) > DATE(NOW() - INTERVAL 1 DAY)
union
SELECT count(item_id) as yesterday from table1
where DATE(creation_date) = DATE(NOW() - INTERVAL 1 DAY)
union
SELECT count(item_id) year_period from table1
where creation_date > now() - interval 1 year;

---

如果您希望提高效率，请这样做，以避免说DATEcreation_date，并使用COUNT*而不是COUNTcolumn。这样，您就可以在创建日期列上使用索引

而且，如果你有那个索引并使用我展示的那种模式，像你最初的查询会比一堆SUMCASE快得多。。。条款。为什么？因为MySQL可以通过执行所谓的

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我想SUMCASE就是你要找的。使用case语句进行创建date@WEI_DBA我将尝试SUMCASE我对查询进行了修改以使用SUMCASE，并解决了我遇到的问题。DATENOW-INTERVAL 1 DAY可以简化为CURDATE-INTERVAL 1 DAY。您的案例还需要0，或者像我一样使用COUNT忽略空值

SELECT 
    SUM(CASE WHEN DATE(creation_date) > DATE(NOW() - INTERVAL 1 DAY) THEN 1 END) as today,
    SUM(CASE WHEN DATE(creation_date) = DATE(NOW() - INTERVAL 1 DAY) THEN 1 END) AS yesterday,
    SUM(CASE WHEN creation_date > now() - interval 1 year THEN 1 END) AS year_period
FROM table1 

SELECT 
   SUM(CASE WHEN DATE(creation_date) > DATE(NOW() - INTERVAL 1 DAY) THEN 1 ELSE 0 END) today,
   SUM(CASE WHEN DATE(creation_date) = DATE(NOW() - INTERVAL 1 DAY) THEN 1 ELSE 0 END) yesterday,
   SUM(CASE WHEN date(creation_date) > now() - interval 1 year THEN 1 ELSE 0 END) last_year
FROM table1

 SELECT count(*) as today 
   FROM table1 
  WHERE creation_date >= CURDATE()

SELECT count(*) as today FROM table1 
WHERE creation_date >= CURDATE()
union
SELECT count(*) as yesterday
 from table1
where creation_date >= CURDATE() - INTERVAL 1 DAY
  and creation_date <  CURDATE()
union
SELECT count(*) year_period from table1
where creation_date >= CURDATE() - interval 1 year;