How to use MySQL.Data dll in Unity

Hi I'm trying to establish the MySQL connection inside Unity 5.5.2f2 version. My default editor is Visual Studio 2015. I installed the Visual Studio tools for Unity Package. Inside my unity project's assets folder, I created a Plugins folder. Inside the Plugins folder, I included the MySql.Data and System.Data dll files. System.Data dll was copied from Unity's file path and MySql.Data dll file was copied from the .Net Connector 6.9.9 File (.Net and Mono Platform). When I open a script in Visual Studio and try to use the dll files, using System.Data statement works but using MySql.Data doesn't work. I don't think Visual studio is not recognizing the dll file at all. Can someone please help me with this? I have seen a lot of posts but didn't really get a clear solution. BTW I'm writing code in C#.