[Flake.]

Theres really no need to set online to the player and the id, try this.

pawn Код:

new query[250];
    mysql_format(MysqlCon, query, sizeof(query), "UPDATE `players` SET `Online`=1 WHERE `user`=%s",
    PlayerName(playerid));
    mysql_tquery(MysqlCon, query, "", "");
//You can also try print(query); for more debuging if this doesn't work, also check your mysql.log