Datastore Service Example

local dataStoreService=game:GetService("DataStoreService") -- Getting/ Requiring the Service and it's Data Model.
-- This allows us to use it's Methods :GetDataStore(), :GetOrderedDataStore(), GetRequestBudgetForRequestType()
local dataStore=dataStoreService:GetDataStore("PlayerData") -- Asking the dataStoreService for this Table of contents.
-- If the above Table of contents doesn't yet exist one will be created with the name provided, PlayerData.
-- This table has Functions already preset by the functions of the Data Store Service Model.
-- Methods for this table: dataStore:GetAsync(), dataStore:SetAsync(), dataStore:RemoveAsync(),
-- dataStore:UpdateAsync(), dataStore:IncrementAsync()
--local SD=game:GetService("ReplicatedStorage"):WaitForChild("Remotes").SaveData -- I've set up a RemoteEvent Instance in this path.
-- You don't need this but it could be helpful if you wanted to allow the player to manually save their data.

game:GetService("Players").PlayerAdded:Connect(function(player) -- Whenever a player joins the game we'll do this...

    local leaderstats=Instance.new("Folder") -- Creating an Instance with the Class Folder.
    leaderstats.Name="leaderstats" -- For any numerical values store within it to be shown on the CoreGUI Leaderboard you need to
    -- Set the name to exactly, "leaderstats".
    -- If you have a custom GUI that displays this information then the name can be anything. Using leaderstats will..
    -- only be useful if you want the values of the Instances below to be shown on the default leaderstats
    leaderstats.Parent=player -- Setting the Folder Instances parent to the Player.

    local Coins=Instance.new("IntValue") -- Creating an Instance with the Class IntValue.
    Coins.Name="Coins" -- name it anything, Cash, cash, Money, money, Moneyz, BigMan420, doesn't matter.
    Coins.Parent=leaderstats -- Putting this IntValue inside the Folder we made above for the player.

    local CoinData -- Just a temporary holder for any Values returned by the PCall Below.
    local success, errormessage=pcall(function() -- PCalls or Protected Calls allow us to call another function/ Method...
    -- Without the risk of crashing, creating errors without our scripts main function, etc.
    -- Basically this just means that if the function errors for any reason we can handle is 'gracefully'
    -- Meaning we know the error occured and was expecting it so now we can make/ execute our fallback plan.
    -- Which I setup a tiny bit of Error handling down below without first encountering an error, I used error prevention.
    -- Of course if it does for some odd reason fail, it will print the reason for failing as we state below.
    -- and yes, you can stack multiple PCalls within a single one if you really wanted or needed to...
        CoinData=dataStore:GetAsync(player.UserId.."-Coins") -- This is the :GetAsync() function/ Method I mentioned...
        -- At the start of the script. This allows us to call a function predetermined by Roblox that..
        -- will get data from a table, the table is the one we created called PlayerData.
        -- This table is stored within the DataStoreService and can get accessed by the :GetDataStore()
        -- Method/ Function I listed at the start of the script.
        -- The :GetAsync() Function requires a Key to index the value of. ~To get the value of the key, provide the key~
        -- Our Keys should be unique since every players data will be saved within this table.
        -- My key is the Players User ID plus -Coins so.. (1234567890-Coins)
        -- Until we set the Value of the Key then it will be equal to nothing or nil.
        -- We can use any Value Type we want, we could even have it return a function if we needed too...
        -- For now we're using normal ole IntValues or Numerical Values.
    end)

    if success and CoinData~=nil then -- If the Protected/ PCall function from above was successful at returning the data we requested...
    -- and the Value isn't equal to nothing at all then we'll set the leaderstats object(s) we created earlier to represent the value...
    -- Returned by the PCall/ Protected Function, A.K.A. The CoinData, that local we made to temporarily store the data...
    -- It's now useful like so...
        warn("The player "..player.Name.." has gotten the coins value data using the key: "..tostring(player.UserId).."-Coins")
        warn("Key = Value")
        warn("The Key used in the table: "..tostring(player.UserId).."-Coins")
        warn("The Value of the Key: "..tostring(CoinData))
    -- Ignore the warnings I made above this was also to help out but they can be removed.
        Coins.Value=CoinData -- This is where we modify that IntValue we created earlier...
        -- We're changing it's Value to the CoinData or Data returned by the PCall using our Temporary local/ placeholder.
    elseif CoinData==nil then -- Error Prevention, Preventing it from doing nothing if it's nil.
        warn("This player doesn't have a value stored on the key: "..tostring(player.UserId).."-Coins")
        local success, errormessage=pcall(function() -- Another PCall to protect the PCall it's inside of...
            dataStore:SetAsync(player.UserId.."-Coins",0) -- Setting a value that isn't nil...
        end)
        if success then
            warn("We've set a numerical value of zero to hold the place of nil instead.")
            Coins.Value=CoinData -- If we was able to succesfully set the Value of the Key we passed then we'll...
            -- Set the IntValue on the leaderstats to this number.
        else
            warn(errormessage) -- If the SetAsync Fails it'll warn the error specific message now.
        end
    else
        warn(errormessage) -- If the GetAsync Fails it'll warn the error specific message now.
    end
end)

game:GetService("Players").PlayerRemoving:Connect(function(plr)
-- Same as PlayerAdded just for whenever a player is leaving...
-- Same information applies here...

    local success, errormessage=pcall(function()
        dataStore:SetAsync(plr.UserId.."-Coins",plr:WaitForChild("leaderstats"):FindFirstChild("Coins").Value)
    end)

    if success then
        warn(plr.Name.." has left and their Coins data was saved! ")
        warn("Key = Value")
        warn("The Key used in the table: "..tostring(plr.UserId).."-Coins")
        warn("The New Value of the Key: "..tostring(plr:WaitForChild("leaderstats"):FindFirstChild("Coins").Value))
    else
        warn(errormessage)
    end
end)

--[[SD.OnServerEvent:Connect(function(Plr)

    local success, errormessage=pcall(function()
        dataStore:SetAsync(Plr.UserId.."-RoleplayName",Plr.leaderstats.Coins.Value)
    end)

    if success then

    else
        warn(errormessage)
    end
end)]]