How to input content for particular topic to database in php?

[yateesh]

I have recent topics displayed on my home page . When i click on any topic , it opens in a new page with full details of that topic . There is an option( a form ) where users can write review for that particular topic .

What i am looking for is , how do i insert data for only that topic , like , on my home page , in recent topics section , i have to display number of reviews of that topic only .

What i thought is , to take that topic's id and insert . But i do not know how to do that .

This is my 1st table for Topics.

 Topic_Id  -  1 , 2 , 3  
 Title  -  First Topic , Second Topic , Third Topic 
 Category_ID  -   3 , 1 , 1  
 Date  -   yyyy-mm-dd
 

This is my 2nd table for Category.

 Category_ID  -  1 , 2 , 3
 Category_name   -  PHP , MYSQL , PDO
 

This is to input .

try 
   {
   $query = $conn->prepare("INSERT INTO `topics`     (title,category_id) VALUES  (:title,:category_id)");
 
   $query->execute(array(
        'title'       => $_POST['title'],
                                    'category_id' => $_POST['category_id'],
                                    )); 
        }
 
catch (PDOException $e) 
   {
   error_log($e->getMessage());
   die($e->getMessage());
   }
 

This is to display on home page .

   $sql = "SELECT * FROM review ORDER by pid DESC limit  0,3";
 
   $q    = $conn->query($sql);
 
   $q->setFetchMode(PDO::FETCH_ASSOC);
 
   while($row = $q->fetch()){
      echo $row['title'];
      echo $row['username'];
   }
 

This is my 3rd table for inserting reviews .

 Topic_ID  -  
 Rating  -  
 Review  -  
 User_ID  -
 

Problem 1 : How do i input topic-id of a particular topic when user fills and submits form into 3rd table ?
Problem 2 : And is there a need of user-id in 1st table because there is also an option for user to insert topics ?
Problem 3 : How do i select number of reviews for a particular topic to display next to it on home page ?

[Rabbit]

We only allow one question per thread in this forum. Please split out questions 2 and 3 into a separate thread. I will respond to question 1 since that it the question in the title.

You will need to output the id to the page so you can pass that onto to page that will insert into the third table. You can use a hidden form element for that if you don't want to show the id on the page.

[yateesh]

In <input type="hidden" /> how do i get that id ?

<form action="ins.php" method="post">
     <input type="hidden" ?? />
     <input type="text" name="rating" />
     <input type="text" name="review" />
     <input name="submit" type="submit" value="Submit"/>
</form>
 

[Rabbit]

<input name="userid" type="hidden" value="use php to output the id" />