c# - how to query nullable datetime in linq -

i calling following query, display latest date fieldname 'uploaddate', experiencing exception error such as:

the entity or complex type 'cdwmodel.database_bd' cannot constructed in linq entities query.","exceptiontype":"system.notsupportedexception","stacktrace":

code:

public ienumerable<database_bd> getdate()     {         var data = (from c in db.database_bd            select new database_bd()            {                uploaddate = c.uploaddate             }).tolist().orderbydescending(c => c.uploaddate).take(1);           return data;     } 

database_bd model class:

public partial class database_bd  {     public nullable<system.datetime> uploaddate { get; set; }  } 

working solution:

public datetime? getdate()     {         return data = db.database_bd.select(d => d.uploaddate)                      .orderbydescending(c => c)                      .firstordefault();     } 

if want display latest date uploaddate, dont need create new database object.

in example data single date value, or null if there no records:

var data = db.database_bd.select(d => d.uploaddate)                          .orderbydescending(c => c)                          .firstordefault(); 

if need return database_bd object, you'd remove select changes output:

public database_bd getdate() {     var data = db.database_bd.orderbydescending(c => c.uploaddate)                              .firstordefault(a => a.uploaddate.hasvalue);      return data; } 

that give newest database_bd object in table.