[Scenario]

You will need to add to this and probably change the "query", but this is a base.

pawn Код:

command(changenick, playerid, params[])
{
    new id, newname[MAX_PLAYER_NAME], pName[MAX_PLAYER_NAME], iName[MAX_PLAYER_NAME], Query[128];
    if(!IsPlayerAdmin(playerid))
        return SendClientMessage(playerid, COLOR_WHITE, "You are not an RCON administrator!");
    if(sscanf(params, "us[23]", id, newname))
        return SendClientMessage(playerid, COLOR_WHITE, "SYNTAX: /changenick [playerid/name] [nickname]");
    if(!IsPlayerConnected(id))
        return SendClientMessage(playerid, COLOR_RED, "That player is not connected!");

    GetPlayerName(playerid, pName, sizeof(pName));
    GetPlayerName(id, iName, sizeof(iName));
    
    format(Query, sizeof(Query), "UPDATE `players` SET `Name` = '%s' WHERE `UserName` = '%s'", newname, iName);
    mysql_query(Query);
    return 1;
}

This uses "sscanf2" and "zcmd" - you'll need 'em!