MySQL FAQs - Managing Tables and Running Queries with PHP Scripts

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By: FYIcenter.com

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How To Query Multiple Tables Jointly?

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:

<?php
  include "mysql_connection.php";

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

  mysql_close($con); 
?>

How To Get the ID Column Auto-Incremented?

Many tables require an ID column to assign a unique ID number for each row in the table. For example, if you have a table to hold forum member profiles, you need an ID number to identify each member. To allow MySQL server to automatically assign a new ID number for each new record, you can define the ID column with AUTO_INCREMENT and PRIMARY KEY attributes as shown in the following sample script:

<?php
  include "mysql_connection.php";

  $sql = "CREATE TABLE fyi_users ("
      . " id INTEGER NOT NULL AUTO_INCREMENT" 
      . ", name VARCHAR(80) NOT NULL"
      . ", email VARCHAR(80)"
      . ", time TIMESTAMP DEFAULT CURRENT_TIMESTAMP()"
      . ", PRIMARY KEY (id)"
      . ")";
  if (mysql_query($sql, $con)) {
    print("Table fyi_users created.\n");
  } else {
    print("Table creation failed.\n");
  }

  mysql_close($con); 
?>

If you run this script, a new table will be created with ID column defined as auto-increment. The sample script below inserts two records with ID values assigned by MySQL server:

If you run this script, you will get something like this:

1 rows inserted.
1 rows inserted.
1, John King, 2006-07-01 23:02:39
2, Nancy Greenberg, 2006-07-01 23:02:39

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