What is the difference between mysql_db_query and mysql_query in PHP and when should each be used?

The main difference between mysql_db_query and mysql_query in PHP is that mysql_db_query is used to specify the database to perform the query on, while mysql_query does not require specifying the database as it is already specified in the connection. mysql_db_query is considered deprecated and should be avoided in favor of mysql_query or mysqli_query for better security and performance. It is recommended to use mysql_query or mysqli_query for executing SQL queries in PHP.

// Using mysql_query to execute a SQL query
$query = "SELECT * FROM table_name";
$result = mysql_query($query);

// Using mysqli_query to execute a SQL query
$query = "SELECT * FROM table_name";
$result = mysqli_query($connection, $query);