Question

I am not sure if that join statement is writen in the right way:

<?php 

function generateComment($commentID)
{

   $avatar_Q=mysql_query("
            SELECT * FROM comments com
            INNER JOIN users us ON com.user_id=us.user_id
            WHERE comment_id=$commentID // will that $commentID be red in that query string or will it treat it as a string "commentID"
   ");
   if($row=mysql_fetch_array($avatar_Q))
   {
       $userName=$row["us.user_name"]; // do I refer to the fields like that
       $avatarPath=$row["us.avatar"];
       $avatarRep=$row["us.reputation"];
       $message=$row["com.comment"];
       $date=$row["com.date"];
   }
   mysql_close();

   if(!isset($avatarPath))
   {
       $avatarPath="blank picture";
   }

?>

Is this the most efficient way to write a join statement

Answer 1

Your query is written correctly, but you can improve it by specifing the table on comment_id, and for a better returning I suggest you to specify with column you want back, also I will use the variable outside the “string”, because it’s a numeric value (I suppose you omit the single quote like…

$sql = "Select com.command_it, etc 
 FROM ..... WHERE com.comment_id = ".$commentID."";

If otherwise the com.comment_id is text or varchar you must use the single quote like:

$sql = "Select com.command_it, etc 
 FROM ..... WHERE com.comment_id = '".$commentID."'";

Moreover this way you get only the rows where there is a user and a comment, if one user have no comment you don’t retrieve that user…

If you want the user also if he has no comments you must use a LEFT JOIN

$sql = "SELECT com.comment_id, etc FROM users us
            LEFT JOIN comments com ON com.user_id=us.user_id
            WHERE com.comment_id=".$commentID."";