Can I Safely Replace All `mysql_` Functions with `mysqli_` Functions in PHP?

Can Blindly Replacing mysql_ Functions with mysqli_ Lead to Adverse Effects?

In the realm of PHP development, the mysql_ function family has been replaced by mysqli_ in PHP 5.5 and subsequently removed in PHP 7. This raises the question of whether one can blindly swap out mysql_ functions with their mysqli_ counterparts.

The answer is no, as the functions are not fully equivalent. While certain functions may perform similarly, subtle differences exist that could introduce unexpected consequences.

Recommended Approach

It is advisable to proceed with caution when transitioning from mysql_ to mysqli_. Some functions require modifications, such as including the connection handle as an argument or converting to object-oriented syntax. For example:

mysql_query() -> mysqli_query($connection, $sql);
mysql_fetch_assoc() -> $result->fetch_assoc()

Converter Tool

To simplify the conversion process, consider using the MySQLConverterTool (https://github.com/philip/MySQLConverterTool). This tool can automatically convert your mysql_ function calls to their mysqli_ equivalents.

Manual Conversion

Alternatively, you can manually update your code by following these steps:

1. Establish a new connection:

   $mysqli = new mysqli($host, $username, $password, $database);

2. Include the connection in query functions:

   $result = mysqli_query($mysqli, $sql);

3. Adjust result fetching:

   while ($row = mysqli_fetch_assoc($result))

4. Close the connection:

   mysqli_close($mysqli);

Conclusion

While it is tempting to blindly replace mysql_ functions with mysqli_, it is essential to proceed with care. By following the recommended approach or utilizing the converter tool, you can ensure a seamless transition that minimizes the risk of adverse effects.

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