Troubleshooting "Unknown Database Error" in PHP When Database Exists in PHPMyAdmin

When connecting to a MySQL database using PHP, developers may encounter the "Unknown database error" even though the database exists in PHPMyAdmin. This issue can be attributed to several factors.

Spelling Errors

Thoroughly review the database name you are attempting to connect to in your PHP code. Ensure that it is spelled correctly and matches the name as it appears in PHPMyAdmin.

Different Database Servers

Verify that both PHPMyAdmin and your PHP code are connecting to the same database server. This is particularly crucial if you have multiple database servers installed on your system. To confirm:

// Get databases from PHPMyAdmin
$phpmyadmin_databases = $mysqli->query('show databases')->fetch_all();

// Get databases from PHP code
$pdo = new PDO("mysql:host=localhost;dbname=mydata","root","");
$php_databases = $pdo->query('show databases')->fetchAll(PDO::FETCH_COLUMN);

var_dump(array_diff($phpmyadmin_databases, $php_databases)); // Show any differences

If the output reveals any differences, check the PHPMyAdmin configuration file to ensure it connects to the correct server.

Other Considerations

• Ensure that the database user has the appropriate privileges to access the database.
• Verify that the database is not corrupted or damaged.
• Check your PHP configuration to ensure that the MySQL extension is enabled.