The page is blank after PHP is connected to MySQL. What is the reason for the invalid die() function?

The page is blank after PHP is connected to MySQL and die() function is invalid.

During PHP connection to MySQL database, the page is blank and the die() function is invalid is a common problem. This article analyzes this problem and provides solutions.

Problem: After the PHP code connects to the MySQL database, the page has no output, and the error message cannot be displayed even if die() function is used.

Cause Analysis: Page blank usually means that the PHP code produces no output. The reason why die() function fails is that die() statement is not reached during the code execution. This is usually because the database connection is successful, resulting in if (!$con) condition being false and die() statement being skipped.

Sample code and questions:

The following code tries to connect to the local MySQL database:

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

If the connection is successful, the code will not output anything and the page will be blank. die() statement is not executed.

Solution:

To display the connection results more clearly, information should be output regardless of whether the connection is successful or failed. You can use the else statement block:

 <?php $con = mysqli_connect("localhost","root","123456");
if (!$con) {
    die("Database connection failed!" . mysqli_connect_error()); //Show more detailed error information} else {
    echo "The database connection is successful!"; // If the connection is successful, this information will be displayed}
?>

Improved code:

• mysqli_connect_error() was added to the die() statement to display more detailed error information and facilitate debugging.
• Added an else statement block to output prompt information when the connection is successful to avoid blank pages.

Through the above modification, even if the database connection is successful, the page will display "Database connection is successful!", thus avoiding confusion caused by no output. This helps developers quickly determine whether the connection is successful and discover and resolve potential problems in a timely manner. If the page blank is still present, you need to check for other aspects, such as:

• Server Configuration: Make sure the MySQL server is running and the PHP environment is correctly configured.
• Permissions issue: Confirm that the MySQL username and password are correct, and that the user has sufficient database access.
• Error log: Check PHP and MySQL error logs for more detailed error information.
• Code Error: Double-check the PHP code to make sure there are no other syntax or logic errors.

Remember that good error handling and output information are the key to debugging PHP code. With clear output, you can position and solve problems more effectively.

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