title: linq to sql how to join on multiple columns and some condition
body: <pre><code>var recordhoursQuery = from  w in crnnsupContext.WorkHoursHistories
                                 join p in crnnsupContext.ProvStates on w.Province equals p.ProvinceStateID
                                 join r in crnnsupContext.Renewals on new {w.WorkYear+1,w.RegNumber} equals new{r.RenewalYear, r.RegNumber}
                                 where r.RegNumber == _username
                                 select new CRecordHours
                                 {
                                     WorkHoursHistory = w,
                                     Renewal = r
                                 };
  </code></pre>
  
  <p>How to implement a+1 equals b? Even when i remove <code>+1</code>, error still came said "The type of one of the expressions in the join clause is incorrect...."</p>