Checking if a RPName already exists?

[Pokinope]

Hello, I'm wondering how to check whether an RPName already exists in DarkRP, I'm currently doing this below, which is what I saw in some DarkRP Forum Thread, but it doesn't seem to work, not sure what I'm doing wrong, any help would be appreciated!
for k, v in pairs( player.GetAll() ) do
    local alreadytaken = sql.Query( "SELECT rpname FROM darkrp_player WHERE uid = '"..v:UserID().."'" )

    for a, b in pairs(alreadytaken) do
        if charname:GetValue() == b then
            charname:SetText( "That RP name is already taken!")
        else
            net.Start( "ChangeRPName" )
                net.WriteString( charname:GetValue() )
            net.SendToServer()

            if IsValid(bg) then
                bg:Remove()
            end
        end
    end
end

[ERROR] addons/character-creation/lua/autorun/client/cc_vgui.lua:4: bad argument #1 to 'pairs' (table expected, got boolean)
  1. pairs - [C]:-1
   2. DoClick - addons/character-creation/lua/autorun/client/cc_vgui.lua:4
    3. unknown - lua/vgui/dlabel.lua:232

[c👌de_g🎷]

alreadytaken will return false instead of a table when your query is invalid - change UserID to SteamID64.

[Pokinope]

Alright, changed it to SteamID64, but still seem to get the same error as above?

[Invule]

you need to do this serverside, not client sided.

[c👌de_g🎷]

Only way that wouldn't work is if the player hasn't declared a unique rpname (used the /rpname command) - otherwise, it will just use their Steam name.

[FireWolf]

DarkRP already prevents one from having the same name as another through /name. The only way to overcome this is if you join a server with the same name as another person on the server. So you can find it through the DarkRP repository on GitHUB.