在MySQL中对多个数据运行相同SELECT的最简单方法

Question

我有一个非常简单的选择,让我们说:

SELECT COUNT(added) FROM users WHERE added < "2015-07-30"

我是否可以以某种简单的方式运行此选择,不仅适用于给定的日期,而且还可以说,7天,每行显示计算到特定日期？

编辑:这是我构建表的SQL:

CREATE TABLE users (
id INT(6) UNSIGNED AUTO_INCREMENT PRIMARY KEY,
 added DATE
);

INSERT INTO users (added) VALUES ("2015-07-30");
INSERT INTO users (added) VALUES ("2015-07-29");
INSERT INTO users (added) VALUES ("2015-07-28");
INSERT INTO users (added) VALUES ("2015-07-21");
INSERT INTO users (added) VALUES ("2015-07-26");
INSERT INTO users (added) VALUES ("2015-07-25");
INSERT INTO users (added) VALUES ("2015-07-24");
INSERT INTO users (added) VALUES ("2015-07-23");
INSERT INTO users (added) VALUES ("2015-07-29");
INSERT INTO users (added) VALUES ("2015-07-22");
INSERT INTO users (added) VALUES ("2015-07-20");
INSERT INTO users (added) VALUES ("2014-02-10");

我期待这样的结果:

    DATE   | Count |
--------------------                   
2015-07-30 |  12   |
2015-07-29 |  11   |   
2015-07-28 |  10   |
2015-07-27 |   9   |
2015-07-26 |   9   |
2015-07-25 |   8   |
2015-07-24 |   7   |

Answer 1

我想你想要这样的东西：

SELECT
  SUM(added >= CURRENT_DATE() - INTERVAL 14 DAY) AS last_14_days,
  SUM(added >= CURRENT_DATE() - INTERVAL 7 DAY) AS last_7_days,
  SUM(added = CURRENT_DATE()) AS today
FROM users
WHERE
  added >= CURRENT_DATE() - INTERVAL 14 DAY

你也可以用它来计算<“2015-07-30”之前和最近7天的所有记录，但它的性能会很差，我建议你使用内联查询：

SELECT
  (SELECT COUNT(added) FROM users WHERE added < "2015-07-30") AS before_30,
  (SELECT COUNT(added) FROM users WHERE added >= "2015-09-08") AS last_7

或 UNION 查询：

SELECT "Before 30" as Interval, COUNT(*) AS total
FROM users WHERE added < "2015-07-30"
UNION ALL
SELECT "Last 7" as Interval, COUNT(*) AS total
FROM users WHERE added >= "2015-09-08"

编辑

根据您的评论，您需要使用 GROUP BY 查询。如果添加的是日期字段（没有时间信息），您可以使用此查询：

SELECT added, COUNT(*)
FROM users
WHERE added >= CURRENT_DATE() - INTERVAL 7 DAY
GROUP BY added

编辑

这应该是您正在寻找的：

SELECT d.added, COUNT(*)
FROM
  (SELECT DISTINCT added
   FROM users
   WHERE added BETWEEN "2015-07-30" - INTERVAL 30 DAY AND "2015-07-30") AS d
  INNER JOIN users
  ON users.added <= d.added
GROUP BY
  d.added
ORDER BY `d`.`added` DESC

SQLFiddle 在这里