Entity Framework - How to reference a column name using a string variable

If I understand your problem statement correctly, you want something like this to work:

Account temp = // with temp coming from a library such as EntityFramework
temp.SetValue(set_col_name, set_col_value);

this is quite easy to achieve with either pure reflection or Linq Expression Trees (which I opted for):

static class Ext
{
    public static void Set<T, TProperty>(this T instance, string propertyName, TProperty value)
    {
        var instanceExpression = Expression.Parameter(typeof(T), "p");
        var propertyGetterExpression = Expression.PropertyOrField(instanceExpression, propertyName);

        //generate setter
        var newValueExpression = Expression.Parameter(typeof(TProperty), "value");
        var assignmentExpression = Expression.Assign(propertyGetterExpression, newValueExpression);
        var lambdaExpression = Expression.Lambda<Action<T, TProperty>>(assignmentExpression, instanceExpression, newValueExpression);
        var setter = lambdaExpression.Compile();// the generated lambda will look like so: (p, value) => p.{your_property_name} = value;
        setter(instance, value);
    }
}

one advantage of this method over pure reflection is that you can build the setter delegate once and call it multiple times at later stage (I will leave this with you to experiment)

with the above in place, hopefully you should be able to do something like this:

    var set_col_name = "is_privileged";
    var set_col_value = true;
    using (ae = new AccountEntities())
    {
        var temp = ae.Accounts.SingleOrDefault(a => a.id == account.id);
        temp.Set(set_col_name, set_col_value);
        temp.Set("acct_name", "test");
        ae.SaveChanges();
    }