Mysql 使用嵌套SQL语句进行筛选而不影响计数

我想知道是否有一种方法可以在不影响计数列的情况下过滤结果。我有订单、员工和服务表。我有一个查询，显示员工完成的服务，统计每个服务的员工数量，并计算每个服务的每个员工的价格。我想做的是只过滤出特定员工完成的服务，但保持员工数量的计数不变。下面的查询显示了我想要的内容，但是每当我向WHERE子句添加一个雇员id时，雇员计数显然会下降到1

SELECT R.`order_id`, R.`service_id`, S.`name` AS 'service_name', Rprice.`price` AS 'service_price', COUNT(R.`employee_id`) AS 'number_employees', ROUND(Rprice.`price` / COUNT(R.`employee_id`), 2) AS 'price_employee_service' FROM `R_services_employees_orders` R
JOIN `R_order_service_price` Rprice ON R.`order_id` = Rprice.`order_id` AND R.`service_id` = Rprice.`service_id`
JOIN `Employees` E ON R.`employee_id` = E.`id`
JOIN `Orders` O on R.`order_id` = O.`id`
JOIN `Services` S on R.`service_id` = S.`id`
WHERE NOT E.`department` = 'o' 
AND O.`completed` BETWEEN '2017-04-26' AND '2017-05-06'
GROUP BY R.`order_id`, R.`service_id`
ORDER BY R.`order_id`, R.`service_id`;

我尝试过使用子查询，但似乎找不到正确的查询。提前谢谢

表结构如下所示

CREATE TABLE `Employees` (
  `id` varchar(3) NOT NULL DEFAULT '',
  `name` varchar(50) DEFAULT NULL,
  `department` varchar(1) DEFAULT NULL COMMENT 'Enter P R or M',
  `active` tinyint(1) DEFAULT '1',
  PRIMARY KEY (`id`)
) ENGINE=InnoDB DEFAULT CHARSET=utf8;


CREATE TABLE `Orders` (
  `id` int(11) unsigned NOT NULL,
  `completed` datetime DEFAULT NULL,
  PRIMARY KEY (`id`)
) ENGINE=InnoDB DEFAULT CHARSET=utf8;

CREATE TABLE `R_order_service_price` (
  `id` int(11) unsigned NOT NULL AUTO_INCREMENT,
  `order_id` int(11) unsigned DEFAULT NULL,
  `service_id` varchar(6) DEFAULT NULL,
  `price` float DEFAULT NULL,
  PRIMARY KEY (`id`),
  KEY `FK_order_price` (`order_id`),
  KEY `FK_service_price` (`service_id`),
  CONSTRAINT `FK_order_price` FOREIGN KEY (`order_id`) REFERENCES `Orders` (`id`) ON DELETE NO ACTION ON UPDATE NO ACTION,
  CONSTRAINT `FK_service_price` FOREIGN KEY (`service_id`) REFERENCES `Services` (`id`) ON DELETE NO ACTION ON UPDATE NO ACTION
) ENGINE=InnoDB DEFAULT CHARSET=utf8;

CREATE TABLE `R_services_employees_orders` (
  `id` int(11) unsigned NOT NULL AUTO_INCREMENT,
  `order_id` int(11) unsigned DEFAULT NULL,
  `employee_id` varchar(3) DEFAULT NULL,
  `service_id` varchar(6) DEFAULT NULL,
  PRIMARY KEY (`id`),
  KEY `FK_order` (`order_id`),
  KEY `FK_service` (`service_id`),
  KEY `FK_employee` (`employee_id`),
  CONSTRAINT `FK_employee` FOREIGN KEY (`employee_id`) REFERENCES `Employees` (`id`) ON DELETE NO ACTION ON UPDATE NO ACTION,
  CONSTRAINT `FK_order` FOREIGN KEY (`order_id`) REFERENCES `Orders` (`id`) ON DELETE NO ACTION ON UPDATE NO ACTION,
  CONSTRAINT `FK_service` FOREIGN KEY (`service_id`) REFERENCES `Services` (`id`) ON DELETE NO ACTION ON UPDATE NO ACTION
) ENGINE=InnoDB DEFAULT CHARSET=utf8;

---

您可以在select中使用CASE语句，例如：

 SELECT SUM(CASE WHEN employee_id = 10 THEN 1 ELSE 0 END) AS employee_order_count...

---

您可以通过这种方式汇总任何特定于员工的度量，从而在正常计算中保持总体汇总。

您可以在select中使用案例陈述，例如：

 SELECT SUM(CASE WHEN employee_id = 10 THEN 1 ELSE 0 END) AS employee_order_count...

---

您可以聚合任何特定于员工的度量，这样可以在正常计算中保持总体聚合。

您可以发布一些表格的示例数据吗？您可以发布一些表格的示例数据吗？谢谢！这很有效，有没有办法把它放在WHERE子句中？比如“员工订单数量=1”之类的？编辑：没关系，我让员工\u订单\u计数=1，效果很好！非常感谢。这很有效，有没有办法把它放在WHERE子句中？比如“员工订单数量=1”之类的？编辑：没关系，我让员工\u订单\u计数=1，效果很好！