How can PHP beginners avoid common mistakes when working with multiple queries and result sets in PHP?

Beginners can avoid common mistakes when working with multiple queries and result sets in PHP by ensuring they properly close each result set after use to free up memory and avoid conflicts between queries. It is also important to use different variable names for each result set to prevent overwriting data unintentionally.

// Example of properly closing result sets and using distinct variable names
$query1 = mysqli_query($connection, "SELECT * FROM table1");
while ($row1 = mysqli_fetch_assoc($query1)) {
    // Process data from table1
}
mysqli_free_result($query1);

$query2 = mysqli_query($connection, "SELECT * FROM table2");
while ($row2 = mysqli_fetch_assoc($query2)) {
    // Process data from table2
}
mysqli_free_result($query2);