What potential issue could cause the error message "No Database Selected" in a PHP script that involves database connections?

The "No Database Selected" error message in a PHP script involving database connections typically occurs when the script fails to specify the database to work with before executing queries. To solve this issue, you need to ensure that you have selected the database using the `mysqli_select_db()` function after establishing the database connection. This function specifies the default database to be used for subsequent queries. 

// Establish database connection
$connection = mysqli_connect("localhost", "username", "password");

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

// Select the database
$db_selected = mysqli_select_db($connection, "database_name");

if (!$db_selected) {
    die("Database selection failed: " . mysqli_error($connection));
}

Keywords

PHP MySQL Database connection mysqli_select_db Error message

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