Executing Custom query -- Entity Framework

You can try somethink like that :

public static partial class ObjectContextExtension
{
    public static T ExecuteScalarCommand<T>(this ObjectContext context, string command)
    {
        DbConnection connection = ((EntityConnection)context.Connection).StoreConnection;
        if (connection.State == ConnectionState.Closed)
            connection.Open();

        DbCommand cmd = connection.CreateCommand();
        cmd.CommandText = command;
        cmd.CommandType = CommandType.Text;

        return (T)cmd.ExecuteScalar();
    }

It add the method "ExecuteScalarCommand" to the ObjectContext.
You just give the SQL request as parameter and the return type for the generic type.