Question

I’m trying to do a join query Linq using VB. I want to return the max EnterTime, but I’m getting an error, saying “

cannot convert System.Linq.Iqueryable(Of Date) to System.Nullable(Of
Date)

How can I resolve this?

     Dim results =
            From b In context.H_Beneficiary
            Join e In context.Employees On b.EmployeeId Equals (e.EmployeeId)
            Join c In context.Companies On e.CompanyId Equals (c.CompanyId) _
            Where e.IntegrationId.Equals(c.CompanyId) _
            And (b.EndDate Is Nothing Or b.EndDate >= DateTime.Today)
            Select b.EnterTime

Answer 1

You Linq query returns a sequence of dates, not a single date. That’s why the assignment won’t work.

To assign the max date from your query, you could sort the query by date, than pick the first result, if any:

Dim results =
        From b In context.H_Beneficiary
        Join e In context.Employees On b.EmployeeId Equals (e.EmployeeId)
        Join c In context.Companies On e.CompanyId Equals (c.CompanyId) _
        Where e.CompanyIntegrationId.Equals(c.CompanyId) _
        And (b.EndDate Is Nothing Or b.EndDate >= DateTime.Today)
        Order By b.EnterTime Descending
        Select b.EnterTime

Dim latestDate As Nullable(Of DateTime) = results.FirstOrDefault()