What are some best practices for structuring PHP scripts that interact with MySQL databases to avoid errors like "no database selected"?

When interacting with MySQL databases in PHP scripts, it is important to ensure that a database is selected before executing any queries to avoid errors like "no database selected". One way to solve this issue is to explicitly select the database using the mysqli_select_db() function before executing any queries. 

// Connect to MySQL database
$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));
}

// Now you can execute your queries safely
mysqli_query($connection, "SELECT * FROM table_name");

Keywords

PHP MySQL database connection mysqli_select_db error handling

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