Error logging and analysis of PHP database connections

Error logging and analysis of PHP database connection

When using PHP for database operations, we often encounter some connection errors, such as failure to connect to the database, failure to connect to the database, etc. Issues such as selecting a database. In order to better locate and solve these problems, we need to log and analyze these connection errors. This article will introduce how to use PHP's error logging feature to capture connection errors, and demonstrate through sample code how to analyze and resolve these errors.

First, we need to enable PHP’s error logging function. In the php.ini configuration file, find the following lines of code:

; error logging
; Error logging file location.
; log_errors = Off
; Log errors to specified file.
; error_log = filename

Modify the value of log_errors to On, and specify the path to an error log file, For example:

log_errors = On
error_log = "/var/log/php_errors.log"

In this way, PHP will write the error information to the specified log file when an error occurs. Next, let's look at how to log errors when a connection error occurs.

Code example:

<?php
$servername = "localhost";
$username = "root";
$password = "password";
$dbname = "test_db";

$conn = mysqli_connect($servername, $username, $password, $dbname);

if (!$conn) {
    error_log("连接数据库失败: " . mysqli_connect_error());
    // 其他处理连接错误的代码
}

// 其他数据库操作代码
?>

In the above example, we use the mysqli_connect() function to connect to the database and pass the mysqli_connect_error() function Get connection error information. If the connection fails, use the error_log() function to write the error message to the log file.

When we run the above code, if a connection error occurs, the error message will be recorded in the specified log file. We can locate the cause of the connection failure by viewing the log file, analyze and resolve the error.

The following is an example:

The contents of the error log file (/var/log/php_errors.log):

[2021-01-01 10:00:00] [error] 连接数据库失败: Access denied for user 'root'@'localhost' (using password: YES)

According to the error message, we can know that the reason is Access denied, failed to connect to the database. The possible reason is that the username or password is wrong, or there is no permission to access. Based on this information, we can try to connect with the correct username and password and check that the user permissions are set correctly.

Through this method of logging and analysis, we can better handle PHP database connection errors and solve problems quickly. During the development and maintenance process, timely recording and analyzing error logs is an efficient method that can improve development efficiency and code quality.

Summary:

This article introduces how to use PHP's error logging feature to capture database connection errors, and demonstrates how to analyze and resolve these errors through sample code. In actual development, timely recording and analyzing error logs is the key to solving problems. It can help us quickly locate and solve connection errors, and improve code quality and development efficiency.

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