Question

我正在为办公室开发一个网络系统，家里的病人可以在系统中注册，这样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，并且还会放置所需的测试类型。我在mysql中有一个名为＆＃34;考试类型＆＃34;其中发现了5种类型的考试，并附有练习方式，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，一切都进展顺利，我想限制可以要求进行一天测试的患者数量，我无法成功实现。

办公室每天只允许20次预约，但每种类型的检查最多只允许5名患者。

我想知道，您怎么能限制每天只有5名患者可以要求进行该类检查？

我不知道如何限制系统的这一部分，我希望他们能帮助我。我感谢任何支持我的人。

Answer 1

请考虑以下事项：

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)

通过预约和考试类型限制患者数量（PHP - MYsql）

1 个答案: