comparing two columns

Zurke · #1 13-Nov-2005, 19:14

Is it possible two compare two columns in a database?

I have never tried to compare two columns so I dont know if it is the way I have written it or if it is even possible.#counts total posts in a thread.

PHP Code:


$query="SELECT * FROM threads WHERE post_id = id";
   $result=mysqli_query($connection,$query);
    if(!$result){
     echo"<b>unable to select total posts @ this time</b>";
       exit();  
    } 
  while
   ($posts = mysqli_num_rows($result)){
    }
   if($posts == 0){$posts = "no replies";}

"post_id" and "id" are the columns.

I am trying to retrieve the number of posts to a thread and place the result on a page next to the listed thread.

Am I making any sense? Can anyone help?

fallen_samurai · #2 13-Nov-2005, 23:22

I am building a forum system right now and it is possible to count posts in a certain thread, or threads in a topic for that matter. The way I did it was by creating separate tables for topics, threads, and posts. And in the threads table I used topic_id (which would equal the "id" field of the topic it belonged to), then in the posts table I made a thread_id (again associating the post to the thread table's "id").

For example (very simple tables):

PHP Code:


topics(id, name, description)
threads(id, topic_id, name, author, timestamp)
posts(id, thread_id, name, author, timestamp)

With these tables you then join them in a SQL search statement:

PHP Code:


$query = "SELECT * FROM topics,threads where threads.topic_id = topics.id";

This is called a class-based query search, in which you use two or more tables and therefore have to associate the field you are looking for to a table by adding the table's name in front of it: TABLENAME.FIELD.

If any of this doesn't make sense, please let me know

Zurke · #3 14-Nov-2005, 18:58

fallen_samurai, I am doing the same thing you are. Only difference is I use one table. When someone makes a post I associate the row number of the thread to the post as a value. post_id gets its number from the id of the thread. At this point I am trying to match them up and count them.

But I cant seem to get it to work.

JdS · #4 15-Nov-2005, 02:21

If you really want some suggestions, you need to supply the table structure with some example data and what you expect to retrieve.

Zurke · #5 15-Nov-2005, 09:10

Quote:

Originally Posted by JdS

If you really want some suggestions, you need to supply the table structure with some example data and what you expect to retrieve.

Hi JdS, I can try and do that.

Table structure:
http://zurke.biz/table.php

Location:
http://zurke.biz/location.php

As you can see in the table structure the post_id has the same number as the thread_id's row 'id'. When a thread is created post_id is '0' and thread_id takes on a section number, that I can group together. When a post is created thread_id is '0' and Post_id takes on the row 'id' of the thread_id to match them up.

I want to count how many post_id's have a particular thread_id, place it into a variable for a while statement and display them as replies/posts to a particular thread. As shown on the "location" document I provided.

If this is not enough info just ask. I can get whatever you need. I have tried for some time to get it to work but I can only put them into an array. An array doesnt work because there could be 10, 20, 100 + posts, who knows?

I appreciate the help. Thanks.

Zurke · #6 16-Nov-2005, 10:45

Quote:

Originally Posted by Zurke

Hi JdS, I can try and do that.

Table structure:
http://zurke.biz/table.php

Location:
http://zurke.biz/location.php

As you can see in the table structure the post_id has the same number as the thread_id's row 'id'. When a thread is created post_id is '0' and thread_id takes on a section number, that I can group together. When a post is created thread_id is '0' and Post_id takes on the row 'id' of the thread_id to match them up.

I want to count how many post_id's have a particular thread_id, place it into a variable for a while statement and display them as replies/posts to a particular thread. As shown on the "location" document I provided.

If this is not enough info just ask. I can get whatever you need. I have tried for some time to get it to work but I can only put them into an array. An array doesnt work because there could be 10, 20, 100 + posts, who knows?

I appreciate the help. Thanks.

correction: I should have written thread_id as id. The correction is in bold.

As you can see in the table structure the post_id has the same number as the thread_id's row 'id'. When a thread is created post_id is '0' and thread_id takes on a section number, that I can group together. When a post is created thread_id is '0' and Post_id takes on the row 'id' of the thread_id to match them up.

I want to count how many post_id's have a particular id, place it into a variable for a while statement and display them as replies/posts to a particular thread. As shown on the "location" document I provided.

If this is not enough info just ask. I can get whatever you need. I have tried for some time to get it to work but I can only put them into an array. An array doesnt work because there could be 10, 20, 100 + posts, who knows?

Also, here is the actual code for the placement of the variable:

# This section is the product of the above query.
echo"<table border='1' background='' bgcolor='' cellpadding='0' cellspacing='0' width='850' height='80' align='center'><tr>";
echo"<td background='' bgcolor='' width='400' align='left'>";view_post();
echo"</td><td background='' bgcolor='' width='150' height='80' align='center'>$author  </td>";
echo"<td background='' bgcolor='' width='100' height='80' align='center'>$date $time  </td>";
echo"<td background='' bgcolor='' width='100' height='80' align='center'>$total  </td>";
echo"<td background='' bgcolor='' width='100' height='80' align='center'>$views  </td>";
echo"</tr></table>";

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