盲目地用 mysqli_ 替换 mysql_ 是一个谨慎的做法吗？

Blindly Replacing mysql_ with mysqli_: A Cautious Approach

Despite being deprecated and removed in PHP 5.5 and 7 respectively, mysql_ functions continue to be prevalent in legacy projects. The question arises whether replacing all mysql_ functions with mysqli_ blindly is feasible, considering its equivalent functionality.

The Answer: Not So Fast

While it may seem convenient to automate the replacement process, the answer is a resounding no. The functionalities of mysql_ and mysqli_ are not entirely equivalent. To avoid potential adverse effects, a more meticulous approach is required.

A Conversion Tool to Ease the Transition

While a blind replacement is inadvisable, there's a helpful conversion tool available: the MySQLConverterTool. This tool assists in updating code to support mysqli_ functions, allowing scripts to function immediately after conversion.

Migrating to Object-Oriented Methodology

In addition to updating the syntax, it's recommended to migrate to an object-oriented methodology for database interactions. This approach provides a cleaner and more flexible code base.

Specific Considerations for Update

• Establish a Connection (mysqli_connect):
  Save the connection to a variable in procedural code: $mysqli = new mysqli($host, $username, $password, $database);
  In OO, use the object syntax: $mysqli->query($sql);
• Executing Queries (mysqli_query):
  Include the connection as the first argument: mysqli_query($mysqli, $sql)
  In OO, use the object method: $mysqli->query($sql)
• Fetching Results (mysqli_fetch_assoc):
  In procedural code: while ($row = mysqli_fetch_assoc($result))
  In OO, use the object function call: while ($row = $result->fetch_assoc())
• Closing the Connection (mysqli_close):
  procedural: mysqli_close($mysqli);
  OO: $mysqli->close();

Remember to apply these principles to other connection and error-handling functions as well. By understanding the subtle differences between mysql_ and mysqli_, and leveraging the available conversion tools, you can successfully update your legacy code without compromising its functionality.

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