How can the error message "Warning: mysql_db_query(): supplied argument is not a valid MySQL-Link resource" be resolved in PHP?

The error message "Warning: mysql_db_query(): supplied argument is not a valid MySQL-Link resource" occurs when the database connection is not properly established before executing a query. To resolve this issue, make sure to establish a connection to the MySQL database using the appropriate functions before executing any queries. 

<?php
// Establish a connection to the MySQL database
$connection = mysqli_connect("localhost", "username", "password", "database");

// Check if the connection is successful
if (!$connection) {
    die("Connection failed: " . mysqli_connect_error());
}

// Perform a query on the database
$query = mysqli_query($connection, "SELECT * FROM table_name");

// Fetch data from the query result
while ($row = mysqli_fetch_assoc($query)) {
    // Process the data
}

// Close the connection
mysqli_close($connection);
?>

Keywords

mysql_db_query MySQL-Link resource error message PHP resolution

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