Eluna Custom XP rates

local T = {} -- A lua table (kind of like array) to store played data when he is logged in

--[[
-- Run to characters DB table
CREATE TABLE `custom_xp_rates ` (
    `guid` INT UNSIGNED NOT NULL,
    `rate` FLOAT NOT NULL,
    PRIMARY KEY (`guid`)
)
COLLATE='utf8_general_ci'
ENGINE=InnoDB
;
]]

-- Loads player rate from DB when he logs in
local function OnLogin(event, player)
    -- Use player's lowguid (DB guid) as the identifier in our data store and DB.
    local guid = player:GetGUIDLow()

    -- Make an SQL query to characters database to a custom table
    local Q = CharDBQuery("SELECT rate FROM custom_xp_rates WHERE guid = "..guid)
    if (not Q) then
        -- Query returned no results, set rate to nothing for the player and return
        T[guid] = nil
        return
    end

    -- If query returned something, set the rate to our data store
    T[guid] = Q:GetFloat(0)
end

local function OnLogout(event, player)
    -- Erase data on logout
    local guid = player:GetGUIDLow()
    T[guid] = nil
end

local function OnSave(event, player)
    -- Actually just loading would be fine, but this is needed if you want to change the rate on the fly ingame.

    -- Save data on player save. Should happen within a set interval and on logout and disconnect etc.
    local guid = player:GetGUIDLow()
    if (not T[guid]) then
        -- no data for player, delete already saved data
        CharDBExecute("DELETE FROM custom_xp_rates WHERE guid = "..guid)
        return
    end

    -- Save (overwrite) the rate the player has
    CharDBExecute("REPLACE INTO custom_xp_rates (rate, guid) VALUES ("..T[guid]..", "..guid..")")
end

local function OnGiveXp(event, player, amount, victim)
    -- Select custom rate or 1 for the player
    local guid = player:GetGUIDLow()
    local rate = T[guid] or 1

    -- Use the rate on the gained XP
    return amount * rate
end

-- Usage:
-- player:SetXPRate(1.4)
-- player:SetXPRate(nil)
function Player.SetXPRate(player, rate)
    -- Select custom rate or 1 for the player
    local guid = player:GetGUIDLow()
    T[guid] = tonumber(rate)
end

RegisterPlayerEvent(3, OnLogin)
RegisterPlayerEvent(4, OnLogout)
RegisterPlayerEvent(25, OnSave)
RegisterPlayerEvent(12, OnGiveXp)