What are the drawbacks of using SELECT * in SQL queries, and how can it be improved for better performance and security in PHP applications?

Using SELECT * in SQL queries can lead to performance issues as it retrieves all columns from a table, even those that are not needed. This can result in unnecessary data transfer and processing. To improve performance and security, it is recommended to explicitly specify the columns needed in the SELECT statement.

// Specify the columns needed in the SELECT statement
$sql = "SELECT column1, column2, column3 FROM table_name WHERE condition";
$result = mysqli_query($connection, $sql);

// Process the query result
if ($result) {
    while ($row = mysqli_fetch_assoc($result)) {
        // Process each row
    }
} else {
    echo "Error: " . mysqli_error($connection);
}