将输入限制为sql表的某个数字

Question

I have a SQL database within which I have a series of different tables. Basically, I am creating an exam day and adding exams to it.

Example:

(examtable) Exam 1

(exams) Physics, Biology, Chemistry, P.E

These both are linked.

Now currently how this works is when I create an exam in the examtable, I can add an unlimited amount of exams to it, but in real life that obviously does not make sense.

So what I am trying to do is have some sort of input when creating the exam that can limit the amount of exams that can be entered to it.

• So for example if I create Exam 2 and limit input to 3, then only 3 exams can be added to it.

I have tried to find something online but cannot seem to get anywhere, could someone please help?

Thanks.

Answer 1

I don't understand very well your question but here it goes:

You can use sql in php to count the number of exams from examstable: 'SELECT COUNT(*) FROM examstable;' And then in PHP : 'if ($no_exams > 3 ) { echo "No more exams can be added."} else insert into the database the exam.'