What is the reason for page blank after PHP is connected to MySQL?

Troubleshooting guide for page blanks after PHP connects to MySQL

Many PHP novices often encounter blank page problems when connecting to MySQL database without any error prompts. This article analyzes this problem and provides solutions.

Problem description: After PHP connects to MySQL database, the page appears blank, and even if die() function is added, it is invalid.

Sample code:

 <?php $con = mysqli_connect("localhost","root","123456");
if (!$con) {
    die("Database connection failed");
}
?>

Problem analysis:

mysqli_connect() function attempts to connect to the MySQL database. If the connection fails, $con is false and !$con is true , execute the die() function and display the error message. But if the connection is successful, $con is the database connection resource, !$con is false , die() will not be executed, and the program will not output any content, resulting in the page blank.

Solution:

1. Verify the connection: Add output statement after the connection is successful:

 <?php $con = mysqli_connect("localhost","root","123456");
if (!$con) {
    die("Database connection failed: " . mysqli_connect_error()); // More detailed error message} else {
    echo "The database connection is successful!"; // Add output statement}
?>

If the page says "Database connection is successful!", the problem is that the code lacks output. If it is still blank, you need to check the following:

2. MySQL Service: Make sure the MySQL service is started.

3. Username and password: Confirm that the username and password are correct.

4. PHP configuration: Check the PHP environment configuration to ensure that the MySQL extension is correctly installed. You can use phpinfo() function to view PHP configuration information and confirm whether mysqli extension has been loaded.

5. Error log: Check the PHP error log for more detailed error information. The log location depends on the server configuration.

6. Permissions issue: Check if the MySQL user has sufficient database access.

7. Code Error: Carefully check for other syntax or logic errors in the PHP code, which may cause the program to fail to execute normally.

8. Character encoding: Ensure that the character encoding of PHP code and MySQL database are consistent, and avoid encoding problems causing page blank.

Through the above steps, you can effectively troubleshoot the reason why the page is blank after PHP is connected to MySQL and find the corresponding solution. Remember that providing detailed error information (such as mysqli_connect_error() ) is crucial to diagnosing problems.

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