Why Does My PHP Code Insert Data Twice in MySQL After Only One Run?

Twice is Once: Understanding MySQL Database Insertion Issues

In a perplexing scenario, a PHP code intended to insert data into a MySQL database unexpectedly inserts the data twice after just one run. The code functions flawlessly on localhost, but the duplication issue arises when it is deployed to a server. Moreover, if the page is refreshed twice, the database only reflects a single result. This perplexing dilemma prompts the question of what factors contribute to this abnormal behavior.

The Hidden Culprit

The answer lies in the browser's request handling. When browsers load a webpage, they send multiple requests, including one for the main script and another for the favicon. In this case, even though the code is executed only once, the presence of the .htaccess file reroutes all requests to the index file, resulting in multiple database insertions.

The Resolution

To resolve this issue, the code should be modified to execute the insertion query only for a specific request, excluding the favicon request. This can be achieved by adding a condition that checks for the existence of the favicon.ico file in the request URI. If the file is absent, signifying a regular page request, the insertion query is executed; otherwise, it is skipped.

Revised Code

The following revised code addresses the issue by introducing the necessary condition:

if (!strpos($_SERVER['REQUEST_URI'], 'favicon.ico')) {
    $result = mysql_query($sql);
}

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