通过预约和检查类型限制患者数量（PHP - MYsql）[关闭]

Question

我正在为一个办公室开发一个网络系统，在家中的患者可以在系统中注册，这样就可以预约特定类型的检查。

当患者请求预约时，他会放置他的个人数据，并放置所需的测试类型。我在 mysql 中有一个名为“exam type”的表，其中找到了 5 种类型的考试以及实践提供的时间表，也就是说，每种类型的考试都是在每天指定的时间间隔内实现的。

到目前为止，一切进展顺利，我想限制可以要求一天进行这种测试的患者数量，但我未能成功实现。

该办公室每天只允许 20 次预约，但每种检查最多只允许 5 名患者。

我想知道，你怎么能限制每天只有 5 位患者可以要求预约该类型的检查？

我不知道如何限制系统的这一部分，我希望他们能帮助我。我感谢任何在我的问题上支持我的人。

Answer 1

考虑以下几点：

DROP TABLE IF EXISTS bookings;

CREATE TABLE bookings 
(booking_id INT NOT NULL AUTO_INCREMENT PRIMARY KEY
,user_id INT NOT NULL
,type INT NOT NULL
,booking_date DATE NOT NULL
,UNIQUE(user_id,booking_date)
);

INSERT INTO bookings (user_id, type, booking_date)
SELECT 1
     , 1
     , '2017-08-05'
  FROM (SELECT 1) x
 WHERE (SELECT COUNT(*)
          FROM bookings
         WHERE booking_date = '2017-08-05'
           AND type = 1) < 5;
Query OK, 1 row affected (0.00 sec)
Records: 1  Duplicates: 0  Warnings: 0

INSERT INTO bookings (user_id, type, booking_date)
SELECT 2
     , 1
     , '2017-08-05'
  FROM (SELECT 1) x
 WHERE (SELECT COUNT(*)
          FROM bookings
         WHERE booking_date = '2017-08-05'
           AND type = 1) < 5;
Query OK, 1 row affected (0.00 sec)
Records: 1  Duplicates: 0  Warnings: 0

INSERT INTO bookings (user_id, type, booking_date)
SELECT 3
     , 1
     , '2017-08-05'
  FROM (SELECT 1) x
 WHERE (SELECT COUNT(*)
          FROM bookings
         WHERE booking_date = '2017-08-05'
           AND type = 1) < 5;
Query OK, 1 row affected (0.00 sec)
Records: 1  Duplicates: 0  Warnings: 0

INSERT INTO bookings (user_id, type, booking_date)
SELECT 4
     , 1
     , '2017-08-05'
  FROM (SELECT 1) x
 WHERE (SELECT COUNT(*)
          FROM bookings

         WHERE booking_date = '2017-08-05'
           AND type = 1) < 5;
Query OK, 1 row affected (0.00 sec)
Records: 1  Duplicates: 0  Warnings: 0

INSERT INTO bookings (user_id, type, booking_date)
SELECT 5
     , 1
     , '2017-08-05'
  FROM (SELECT 1) x
 WHERE (SELECT COUNT(*)
          FROM bookings
         WHERE booking_date = '2017-08-05'
           AND type = 1) < 5;
Query OK, 1 row affected (0.00 sec)
Records: 1  Duplicates: 0  Warnings: 0

SELECT * FROM bookings;
+------------+---------+------+--------------+
| booking_id | user_id | type | booking_date |
+------------+---------+------+--------------+
|          1 |       1 |    1 | 2017-08-05   |
|          2 |       2 |    1 | 2017-08-05   |
|          3 |       3 |    1 | 2017-08-05   |
|          4 |       4 |    1 | 2017-08-05   |
|          5 |       5 |    1 | 2017-08-05   |
+------------+---------+------+--------------+
5 rows in set (0.00 sec)

INSERT INTO bookings (user_id, type, booking_date)
SELECT 6
     , 1
     , '2017-08-05'
  FROM (SELECT 1) x
 WHERE (SELECT COUNT(*)
          FROM bookings
         WHERE booking_date = '2017-08-05'
           AND type = 1) < 5;
Query OK, 0 rows affected (0.00 sec)
Records: 0  Duplicates: 0  Warnings: 0

SELECT * FROM bookings;
+------------+---------+------+--------------+
| booking_id | user_id | type | booking_date |
+------------+---------+------+--------------+
|          1 |       1 |    1 | 2017-08-05   |
|          2 |       2 |    1 | 2017-08-05   |
|          3 |       3 |    1 | 2017-08-05   |
|          4 |       4 |    1 | 2017-08-05   |
|          5 |       5 |    1 | 2017-08-05   |
+------------+---------+------+--------------+
5 rows in set (0.00 sec)