How To Query Multiple Tables Jointly


How To Query Multiple Tables Jointly? - MySQL FAQs - Managing Tables and Running Queries with PHP Scripts



If you want to query information stored in multiple tables, you can use the SELECT statement with a WHERE condition to make an inner join. Assuming that you have 3 tables in a forum system: "users" for user profile, "forums" for forums information, and "posts" for postings, you can query all postings from a single user with a script as shown below:

  include "mysql_connection.php";

  $userID = 101;
  $sql = "SELECT posts.subject, posts.time,,
    . " forums.title"
    . " FROM posts, users, forums"
    . " WHERE posts.userID = ".$userID
    . " AND posts.userID ="
    . " AND posts.forumID =";
  $rs = mysql_query($sql, $con);
  while ($row = mysql_fetch_assoc($rs)) {
    print($row['subject'].", ".$row['time'].", "
      .$row['name'].", ".$row['title']."\n");


2007-05-11, 5774👍, 0💬