How to save multiple values in a datastore?

In a data store we save data as a table to save on the number of requests needed to load / save the players data due to a limited request count.

This table is saved in a JSON format then saved (this is all managed by roblox) and then decoded giving us back the original table of data we saved. We cannot save a mixed table ie a table with both an array part and a key value part as this is not compatible with the JSON format.

To access data we use its key to get the associated data which will be nil if there is no data or the data saved. In most cases we want the key to be unique so we simply add the UserId, I would recommend that you include a prefix such as usr_ ect as you may want to use more than one key for that user.

Putting it all together:-

local Data = game:GetService('DataStoreService'):GetDataStore('Data0')

local prefix = 'user_' -- example prefix


game.Players.PlayerAdded:connect(function(player)
    local folder = Instance.new('Folder')
    folder.Name = 'Leaderstats'

    local credits = Instance.new('IntValue',folder)
    credits.Name = 'Credits'

    local lapAmmount = Instance.new('IntValue',folder)
    lapAmmount.Name = 'LapAmmount'

    local plrData = Data:GetAsync(prefix  .. tostring(player.UserId))
	
    if plrData then
          credits.Value = plrData[1] or 0
          lapAmmount.Value = plrData[2] or 0
   else
        -- most people like to save the data if they have none 
       
	Data:SetAsync(prefix  .. tostring(player.UserId), {
	    credits.Value,
	    lapAmmount.Value        
	 })
   end
  
end)

game.Players.PlayerRemoving:connect(function(player)
    Data:SetAsync(prefix  .. tostring(player.UserId), {
        player.Leaderstats.Credits.Value,
        player.Leaderstats.LapAmmount.Value 
    })
end)

This is a very basic example with duplicate code, I hope this helps.