[code]

$str="east";
$msg_id="abc";
$str_p="ok";
$find_sql="select * from groups where `UserGroup` like '$str'";
$find_result=mysqli_query($conn,$find_sql);
$find_check=mysqli_num_rows($find_result);
if($find_check < 1 ) { echo " 존재하지 않습니다";}
else {
while($user_fetch=mysqli_fetch_assoc($find_result)) {
$user_id=stripslashes($user_fetch['UserId']);
$update="update groups set GetMessage = '$str_p' where UserId = '$user_id' and GroupIdx >=1;";
$run=mysqli_query($conn,$update);
}
$delete="UPDATE `groups` SET `GetMessage` = ''  where `UserId` like '$msg_id' and `GroupIdx` >=1;";
$delete_run=mysqli_query($conn,$delete);

}
[</code]

SQL은 첨부.

변형해서 그룹끼리 할수도 있다.