c# - linq check if matches null or selected item -

i checking see if items match whats in mssql db. using linq update records. know how can check if item equal d_0_2 or if equal null/empty. how go doing this?

below existing code, partially works. failing due null/empty

 if (updateproduct.studioid == convert.toint32(d_0_2.selectedvalue)) { }  else { updateproduct.studioid = convert.toint32(d_0_2.selectedvalue);} 

thanks in advance.

string value = d_0_2.selectedvalue.tostring(); // if selectedvalue empty or null? if (!string.isnullorempty(value))     return; // if product null? if (updateproduct != null)     return;  if (updateproduct.studioid != null &&     updateproduct.studioid == convert.toint32(value)) {     // have product , id equal d_0_2.selectedvalue } else {     // studioid not equal to d_0_2.selectedvalue     updateproduct.studioid = convert.toint32(value); }