Linq where column == (null reference) not the same as column == null
I came across a rather strange problem with linq-to-sql. In the following example,

    var survey = (from s in dbContext.crmc_Surveys
                                       where (s.crmc_Retail_Trade_Id == tradeId) && (s.State_.Equals(state))
                                       select s).First();

If tradeId is null, it doesn't behave as if I had specified null specifically like this instead,

    var survey = (from s in dbContext.crmc_Surveys
                                       where (s.crmc_Retail_Trade_Id == null) && (s.State_.Equals(state))
                                       select s).First();

Which is my desired behavior. In fact it doesn't return anything unless both values are non-null. I can't figure out how to accomplish this short of several different linq queries. Any ideas?
Linq where column == (null reference) not the same as column == null
===

I came across a rather strange problem with linq-to-sql. In the following example,

    var survey = (from s in dbContext.crmc_Surveys
                                       where (s.crmc_Retail_Trade_Id == tradeId) && (s.State_.Equals(state))
                                       select s).First();

If tradeId is null, it doesn't behave as if I had specified null specifically like this instead,

    var survey = (from s in dbContext.crmc_Surveys
                                       where (s.crmc_Retail_Trade_Id == null) && (s.State_.Equals(state))
                                       select s).First();

Which is my desired behavior. In fact it doesn't return anything unless both values are non-null. I can't figure out how to accomplish this short of several different linq queries. Any ideas?