Question

My coworker wrote a package in VB.NET to manipulate strings. I have been asked to implement them through CLR. The package accesses a reference database on the same server as the CLR dll file deployed to standardize the strings. I imported the package to my CLR code to create the functions for SQL Server.

After I deploy the dll file to sql server, the functions work fine except occasionally I get the error

System.NullReferenceException: Object reference not set to an instance of an object.

I have to execute my query several times to make it work. It seems the table is locked or sleeping. My query is like

SELECT EMAIL_ADDRESS, dbo.ufn_getEmailDomain(Email_Address) AS EDOMAIN FROM CONTACT_TEMP
WHERE Email_Address IS NOT NULL AND Email_Address<>”

dbo.ufn_getEmailDomain is the CLR function.

There is no online access to this server at all. I searched for a while and couldn’t find why this error comes up occasionally or how to fix it.

Your feedback is greatly appreciated.

my CLR functions here.

<Microsoft.SqlServer.Server.SqlFunction(DataAccess:=DataAccessKind.Read)> _
Public Shared Function ufn_getEmailDomainSLD(ByVal email As String) As String

    If email Is Nothing Then
        Return Nothing
    End If

    Dim de As New DataEmail(email)
    Dim dm As New DataDomain
    Dim emailDomain As String
    dm = de.Domain

    emailDomain = dm.SLD

    Return emailDomain
End Function

Answer 1

I found the reason eventually. In the connection string in the CLR code, I should set ENLIST=FALSE because it connects to a different database. Once I set ENLIST=FALSE, the problem seems to be fixed.