Can Blindly Replacing mysql_ Functions with mysqli_ Lead to Issues?

Updating your codebase to PHP 7 entails replacing deprecated mysql_ functions with their mysqli_ counterparts. However, a common misconception is that you can make this replacement directly across the board.

The Answer: No, It's Not That Simple

While the function names may appear similar, mysqli_ functions have different method signatures and capabilities compared to mysql_. Blindly replacing them could lead to unexpected behavior and potential errors.

The Conversion Process

To ensure a smooth transition, it's crucial to understand the differences between MySQL and MySQLi. One way to mitigate the replacement challenge is to utilize the MySQLConverterTool: https://github.com/philip/MySQLConverterTool. This automated tool assists in converting your codebase to modern MySQLi syntax.

Key Differences in Code Structure

Apart from the direct function replacements, consider the following structural changes:

• Connection: Use mysqli_connect() to create a persistent connection, saving it to a variable for use throughout your codebase.
• Querying: For queries, specify the $mysqli connection variable as the first argument (procedural) or as the object on which the method is called (object-oriented).
• Result Fetching: Use mysqli_fetch_assoc() or $result->fetch_assoc() to retrieve the next row of a result set.
• Closing the Connection: Close the database connection using mysqli_close() or the $mysqli->close() object method.

Conclusion

While the task may seem daunting, the switch to MySQLi is crucial for PHP projects. Utilizing the MySQLConverterTool and understanding the specific changes required in your codebase will ensure a smooth migration process without compromising functionality.