Ya but what is the command ? I dont know noting about sql
mysql_connect("host","user","pass") or die("DB connection failed.");
mysql_select_db("db_name") or die("Couldnt't select DB.");
$query = mysql_query("SELECT * FROM table");
$row = mysql_fetch_array($query);
$comments = $row['comment'];
$my_comment = "Your comment goes here";
$final_query = mysql_query("UPDATE table_name SET comments='$my_comment'");
if ($final_query)
{
echo "Comments replaced.";
exit;
}
else
echo "Something went wrong.";
This is really basic php script to replace all comments with one comment. I haven't tried it but it should work. I didn't want to make it too long, if someone needs advanced script lemme know. And yeah, i almost forgot to mention, you need to replace your info on first line also on second line as well as third line, five, six and seven line too

if everything worked fine you should see "Comments replaced.".