c# - Linq two classes with foreign key -

i have 2 table

class {     int ida;     string desca; }  class b {     int idb;     string descb;     int ida; } 

ida in "b" foreign key class a, , have function return list of "a" getlista() , function have count how many "b" has descb empty, did:

var emptydescb = getlista().where(p => p.b.all(k => k.descb != 0)).count(); 

but isnt working how should :/ . idea guys can count how many empty descb have?

the c# classes , linq query gave example don't match, answer bit of assumption.

the classes below set one-to-many relationship between a , b; i.e. each a instance can have multiple child b instances.

public class {     public int id { get; set; }     public string description { get; set; }      public virtual icollection<b> children { get; set; } }  public class b {     public int id { get; set; }     public string description { get; set; }      public int parentid { get; set; }     public virtual parent { get; set; } } 

.. , given function getlista() returns list of instances of a, can find "number of instances of b description empty" with:

var numberofbwithemptydescriptions = getlista()         .selectmany(a => a.children) // .. ignore 'a' instances, access children, instances of b         .count (b => string.isnullorempty(b.description)); // .. count intances of b empty description