Database Error (Sqlite) in unity 4.0

Post code.

Have you import the necessary package containing the definition of IDbConnection?

Yes , I have imported necessary packages.

 import UnityEngine;
 import System;
 import System.Collections;
 import System.Data;
 import System.Data.Linq;
 import $$anonymous$$ono.Data.Sqlite;
 import DbLinq;

Also , If i put my script in Plugins/Editor folder or Assets/Editor folder , the errors are gone. But then I cant access this script in other scripts . I dont understand this.

 static var databaseName : String = "my_db.sqlite";
 class Database 
 {
     var connection : String;
     var dbcon : IDbConnection;
     var dbcmd : IDbCommand;
     var reader : IDataReader;
     
     function OpenDB()
     {
         if(Application.platform == RuntimePlatform.IPhonePlayer)
         {
             connection = "URI=file:" + Application.dataPath.Replace("/Data","/") + databaseName;
             //connection = "URI=file:" + Application.persistentDataPath + "/" + databaseName;
         }
         else
         {
             connection = "URI=file:" + databaseName; 
         }
         
         Debug.Log("DB  Path : " + connection);
         dbcon.Open();
     }
 }

After putting my script in Editor folder, All errors are gone. Then I access my script as following :

var db : Database = new Database(); db.OpenDB();

And I got the error :

BCE0018: The name 'Database' does not denote a valid type ('not found').