How to Migrate from MySQL to MySQLi for Database Queries: A Step-by-Step Guide

Updating from MySQL to MySQLi for Querying Databases

As MySQL has been deprecated, many developers are updating their code to use MySQLi. However, the transition can be challenging for those unfamiliar with MySQLi's syntax. This article provides a starting point for transforming a MySQL query into its MySQLi equivalent.

Original MySQL Code:

$sql_follows="SELECT * FROM friends WHERE user1_id=".$_SESSION['id']." AND status=2 OR user2_id=".$_SESSION['id']." AND status=2";
$query_follows=mysql_query($sql_follows) or die("Error finding friendships");
if($query_follows>0){
}

MySQLi Code Equivalent:

$Your_SQL_query_variable = mysqli_query($connectionvariable, "SELECT * FROM friends WHERE user1_id=".$_SESSION['id']." AND status=2 OR user2_id=".$_SESSION['id']." AND status=2");
if ($mysqli->errno) {
    printf("Error: %s\n", $mysqli->error);
}

Additional Tools and Resources:

• MySQL Converter Tool: https://github.com/philip/MySQLConverterTool

  • This tool generates MySQLi code from MySQL code. Note that the generated code may contain冗余的代码。

• MySQL Shim Library: https://github.com/dshafik/php7-mysql-shim

  • This library provides a compatibility layer between MySQL and MySQLi, allowing developers to use MySQL functions with the MySQLi syntax.

Important Considerations:

• The mysql_query function in the original code has been replaced with mysqli_query in the MySQLi equivalent.
• Error handling has been modified to use $mysqli->errno and $mysqli->error for more detailed error information.
• When using the MySQL Shime Library, developers should be aware that the library provides an abstraction layer, potentially introducing additional performance overhead.

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