Introduction:
To go with signup.php I will continue introducing you how to write code for checkup.php file which is used to look up the username in the database and returns a string indicating whether it has been already been taken.
checkup.php
<?php require_once 'functions.php'; if (isset($_POST['user'])) { $user = sanitizeString($_POST['user']); $result = queryMysql("SELECT * FROM members WHERE user='$user'"); if ($result->num_rows) echo "<span class='taken'> ✘ " . "This username is taken</span>"; else echo "<span class='available'> ✔ " . "This username is available</span>"; } ?>
As we can see, it relies on the functions sanitizeString and queryMysql. Therefore, the program first includes the file functions.php.
Then, if the $_POST variable user has a value, the function looks it up in the database and, depending on whether it exists as a username, outputs either “This username is taken” or “This username is available.” Just checking the function mysql_num_rows against the result is sufficient for this, as it will return 0 for not found, or 1 if it is found.
The HTML entities ✘ and ✔ are also used to preface the string with either a cross or a checkmark. Below is an example new user creates an account which is already existed in the database.
Fig. 1. Duplicated account error.
Conclusion:
In this section I helped you to write code for checkup.php file combined with signup.php file to do checking and creating a new user account for the site. I hope that you can find useful information in this section.
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