LINQ to Entities newbie question

I'm not an experienced C# programmer and currently I'm doing some stuff with EF 3.5 and LINQ.

I have the following method and I'm quite sure it can be written in a better / shorter way.

Thanks for the help!

  public List<CustOrder> GetOrders(string supplierId, string locationId)
    {
        using (var ctx = new OrderEntities())
        {
            if (!string.IsNullOrEmpty(locationId))
            {
                var result = (from order in ctx.CustOrder
                              where order.SupplierId == supplierId
                                 && order.LocationId == locationId
                              select order).ToList();
                return result;
            }
            else
            {
                var result = (from order in ctx.CustOrder
                              where order.SupplierId == supplierId
                               开发者_开发问答  && order.LocationId != ""
                              select order).ToList();
                return result;              
            }
        }
    }

My mistake: In 2nd linq query, the following line should be removed:

&& order.LocationId != ""

I would recommend this version as I find it more readable IMHO.

public List<CustOrder> GetOrders(string supplierId, string locationId)
{
    using (var ctx = new OrderEntities())
    {
        var query = from order in ctx.CustOrder
                    where order.SupplierId == supplierId
                    select order;

        if (!string.IsNullOrEmpty(locationId))
        {
            query = query.Where(o => o.LocationId == locationId)
        }

        return query.ToList();
    }
}

you can do

 public List<CustOrder> GetOrders(string supplierId, string locationId)
 {
        using (var ctx = new OrderEntities())
        {
             var result = (from order in ctx.CustOrder
                          where order.SupplierId == supplierId
                          && string.IsNullOrEmpty(locationId) ? true : order.LocationId == locationId
                                  select order).ToList();
             return result;
       }
 }

Bala's does the null check and Talljoe's does the empty string check. But this one does both:

 public List<CustOrder> GetOrders(string supplierId, string locationId)
 {
        using (var ctx = new OrderEntities())
        {
             var result = (from order in ctx.CustOrder
                                  where order.SupplierId == supplierId
                                     && ((String.IsNullOrEmpty(locationId) && order.LocationId == locationId) || 
                                         order.LocationId.Length > 0)
                                  select order).ToList();
             return result;
       }
 }

Also, checking string length is usually better than equality check against an empty string.

var result = (from order in ctx.CustOrder
                          where order.SupplierId == supplierId
                             && (String.IsNullOrEmpty(locationId)
                               || order.LocationId == locationId)
                          select order).ToList();
            return result;