如何使用PHP插入组复选框值？

PHP code

$sql = "INSERT INTO user_details (check_box)
VALUES ('$_POST[check_box]')";

Below is my html code

<input type="checkbox" name="check_box[]" value="1"> Group 1<br>
<input type="checkbox" name="check_box[]" value="2"> Group 2<br>
<input type="checkbox" name="check_box[]" value="3"> Group 3<br>

This can be done in this way:

$sql =  "INSERT INTO user_details (check_box) VALUES ("
        . implode('), (',$_POST[check_box])
        . ")";

this is open to mysql injections!! Better do

$clean = array_map('intval',$_POST[check_box]);

before using it.