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mysqli::debug is a very useful method in PHP for debugging MySQL database connections and queries. It can help developers understand some internal details in database communication and track SQL errors, query processes and other information. mysqli::debug will output debug information to the PHP error log or page.
mysqli::debug(string $message): void
This method receives a string as a parameter to define a debug message. In most cases, debug information is automatically generated, but it can also be used to output debug messages manually.
This method has no return value. Its main function is to output debugging information.
Here is a simple example showing how to use mysqli::debug in PHP:
<?php
// Create a database connection
$mysqli = new mysqli("localhost", "user", "password", "database");
// Check if the connection is successful
if ($mysqli->connect_error) {
die("Connection failed: " . $mysqli->connect_error);
}
// Activate debug information
mysqli::debug("Start debugging the database connection");
// Execute a query
$result = $mysqli->query("SELECT * FROM users");
// Output query results
if ($result) {
while ($row = $result->fetch_assoc()) {
echo "userID: " . $row["id"] . " - user名: " . $row["username"] . "<br>";
}
} else {
echo "Query failed: " . $mysqli->error;
}
// Close the database connection
$mysqli->close();
?>
In this example, mysqli::debug is used to output a debug information indicating the start of the database connection. In fact, mysqli::debug is often used to display internal information of database connections, especially during development stages or when encountering complex database problems.
When mysqli::debug is called, it outputs debug information to the PHP error log. If you want to output debug information directly to the browser, you can use the following code:
ini_set('display_errors', 1); // Display error message
error_reporting(E_ALL); // Show all errors
Troubleshooting connection issues <br> When you encounter a database connection failure, you can use mysqli::debug to see if there are more detailed error information to help you troubleshoot the problem.
SQL query debugging <br> When debugging SQL queries, you can use this method to track whether the query is executed correctly and to view the actual operation of the SQL queries.
Performance Monitoring <br> If you suspect that some SQL queries are not performing well, mysqli::debug can help you check the execution time of the query and help you optimize database queries.
mysqli::debug is mainly used in the development stage. It is best to disable debug output in the production environment to avoid exposing sensitive information.
The output of this method will be recorded in the PHP error log file, so it can be further debugged based on the log information.
URL replacement processing part:
When you are debugging a database connection, external resources or requests may be involved. For example, suppose you want to access an external API interface to handle some database operations, the domain name of the URL will point to an external service. To demonstrate how to replace these domains with m66.net , you can replace them directly in the URL:
