How can developers ensure that error messages, including those from mysql_error(), are properly displayed and logged in PHP applications?

Developers can ensure that error messages, including those from mysql_error(), are properly displayed and logged in PHP applications by setting the error reporting level to include E_ALL and enabling error logging in the php.ini file. Additionally, developers can use the mysqli_error() function to retrieve error messages specifically from MySQL queries and handle them appropriately in their code. 

// Set error reporting level to include E_ALL
error_reporting(E_ALL);

// Enable error logging in php.ini file
ini_set('display_errors', 1);
ini_set('log_errors', 1);
ini_set('error_log', '/path/to/error.log');

// Connect to MySQL database
$mysqli = new mysqli("localhost", "username", "password", "database");

// Check for connection errors
if ($mysqli->connect_error) {
    error_log("Connection failed: " . $mysqli->connect_error);
    die("Connection failed: " . $mysqli->connect_error);
}

// Execute MySQL query
$result = $mysqli->query("SELECT * FROM table");

// Check for query errors
if (!$result) {
    error_log("Query failed: " . $mysqli->error);
    die("Query failed: " . $mysqli->error);
}

// Process query results
while ($row = $result->fetch_assoc()) {
    // Process each row
}

// Close connection
$mysqli->close();

Keywords

PHP error messages mysql_error() logging applications

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