public OnPlayerConnect(playerid)
{
    new query[128]; //We use this variable to format our query
    GetPlayerName(playerid, Name[playerid], 24); //Getting player's name
    GetPlayerIp(playerid, IP[playerid], 16); //Getting layer's IP
    mysql_format(mysql, query, sizeof(query),"SELECT `Password`, `ID` FROM `players` WHERE `Username` = '%e' LIMIT 1", Name[playerid]);
    mysql_tquery(mysql, query, "OnAccountCheck", "i", playerid);
    return 1;
}

public OnDialogResponse(playerid, dialogid, response, listitem, inputtext[])
{
switch(dialogid)
    {
        case dlogin: //login dialog
        {
            if(!response) {Kick(playerid);} //if they clicked Quit, we will kick them
            new hpass[129]; //for password hashing
            new query[100]; // for formatting our query.
            WP_Hash(hpass, 129, inputtext); //hashing inputtext
            if(!strcmp(hpass, PlayerInfo[playerid][Password])) //remember we have loaded player's password into this variable, pInfo[playerid][Password] earlier. Now let's use it to compare the hashed password with password that we load
            { //if the hashed password matches with the loaded password from database
                mysql_format(mysql, query, sizeof(query), "SELECT * FROM `players` WHERE `Username` = '%e' LIMIT 1", Name[playerid]);
                //let's format our query
                //We select all rows in the table that has your name and limit the result to 1
                mysql_tquery(mysql, query, "OnAccountLoad", "i", playerid);
                //lets execute the formatted query and when the execution is done, a callback OnAccountLoad will be called
                //You can name the callback however you like
            }
            else //if the hashed password didn't match with the loaded password(pInfo[playerid][Password])
            {
                //we tell them that they have inserted a wrong password
                ShowPlayerDialog(playerid, dlogin, DIALOG_STYLE_INPUT, "Login", "In order to play, you need to login\nWrong password!", "Login", "Quit");
            }
        }
        case dregister: //register dialog
        {
            if(!response) {Kick(playerid);} //if they clicked Quit, we will kick them
            if(strlen(inputtext) < 6) return ShowPlayerDialog(playerid, dregister, DIALOG_STYLE_INPUT, "Register", "In order to play, you need to register.\nYour password must be at least 6 characters long!", "Register", "Quit");
            //strlen checks a lenght of a string. so if player types their password that is lower than 6, we tell them; Your password must be at least 6 characters long!
            new query[300];
            WP_Hash(PlayerInfo[playerid][Password], 129, inputtext); //hashing inputtext
            mysql_format(mysql, query, sizeof(query), "INSERT INTO `players`(`Username`,`Password`,`IP`,`pAdmin`,`pDonateRank`,`pCash`,`pPos_x`,`pPos_y`,`pPos_z`) VALUES ('%e', '%s', '%s', 0, 0, 0, 0.0, 0.0, 0.0)", Name[playerid], PlayerInfo[playerid][Password], IP[playerid], PlayerInfo[playerid][pAdmin], PlayerInfo[playerid][pDonateRank], PlayerInfo[playerid][pCash], PlayerInfo[playerid][pPos_x], PlayerInfo[playerid][pPos_y], PlayerInfo[playerid][pPos_z]);
            //Now let's create a new row and insert player's information in it
            mysql_tquery(mysql, query, "OnAccountRegister", "i", playerid);
            //let's execute the query
        }
    }