SWQL Studio Error (Unknown dataprovider type 'ntext')

EDIT:My question in bold underline below still stands, even though I know some of the answer now (see my Edits further below), but if you look at my final edit (Edit 3:) you can see my workaround that will hopefully help anyone else that wants to make an events report or needs a SWQL query for a script they may be working on for Events.

When joining the Orion.Events table (or entity, or whatever it's called in SWQL.) to the Orion.NetObjectTypes table ON Events.NetObjectType = NetObjectTypes.Prefix I get the error Unknown dataprovider type 'ntext'.  Both objects are of type "System.String" in their table.  When I query the Orion.NetObjectTypes table on its own the Prefix field comes back just fine, but joining on it seems to cause this problem.  The only thing I can think of is that the NetObjectTypes table isn't data that is in the SQL database and (I assume) must be generated by the application and fed into SWIS as an entiy.  Maybe for some reason this causes a problem. I don't know.

Anyone (tdanner especially) know why I can't join Event NetObjectTypes to NetObjectTypes Prefix?

Here is the actual code:

SELECT TOP 1000
e.EventID,
et.Name AS EventTypeName,
e.Message AS EventMessage,
e.NetObjectType,
nt.Name AS ObjectType,
e.NetObjectValue,
e.NetworkNode,
e.InstanceType,
e.EventTime
FROM Orion.Events e
JOIN Orion.EventTypes et ON e.EventType = et.EventType
JOIN Orion.NetObjectTypes nt ON e.NetObjectType = nt.Prefix

I've tried putting the NetObjectTypes table in a subselect in the FROM statement and joining to the results of that but that doesn't seem to trick the query plan and I get the same error.  Besides doing a billion CASE statements for the Orion.Events "NetObjectType" field, what can I do here?

EDIT 1: Also noticed that the NetObjectTypes table has some blank Prefixes that still have a type associated with them.  What's this all about:

EDIT 2:  Also just noticed that there are many duplicate prefixes with different Name matches.  I'm sure that will cause a problem, but I wouldn't think it would be an "Unknown dataprovider type" error.  Why are there either duplicate prefix/name combos, or duplicate prefixes mapping to different names?  How does the program use these items and know how to map duplicate prefixes to the different Name fields?

Orion.NetObjectTypes

EDIT 3: My question above still stands, but I went ahead and used Excel to create all of the CASE statements necessary to map the object type codes (Orion.Events.NetObjectType) to the object type names (based on the Orion.NetObjectTypes.Name field, but modified a bit to fix the duplicates and NULL values):

SELECT TOP 10000  e.EventID,  et.Name AS EventTypeName,  e.Message AS EventMessage,  CASE  WHEN e.NetObjectType = 'AA' THEN 'Application'  WHEN e.NetObjectType = 'ABIA' THEN 'AppInsight for IIS: Application'  WHEN e.NetObjectType = 'ABIP' THEN 'AppInsight for IIS: Application Pool'  WHEN e.NetObjectType = 'ABIR' THEN 'AppInsight for IIS: Request'  WHEN e.NetObjectType = 'ABIRD' THEN 'AppInsight for IIS: Request Details'  WHEN e.NetObjectType = 'ABIS' THEN 'AppInsight for IIS: Site'  WHEN e.NetObjectType = 'ABISB' THEN 'AppInsight for IIS: Site Binding'  WHEN e.NetObjectType = 'ABSA' THEN 'AppInsight for SQL: Application'  WHEN e.NetObjectType = 'ABSD' THEN 'AppInsight for SQL: Database'  WHEN e.NetObjectType = 'ABSF' THEN 'AppInsight for SQL: Database File'  WHEN e.NetObjectType = 'ABSJ' THEN 'AppInsight for SQL: Job Info'  WHEN e.NetObjectType = 'ABSQ' THEN 'AppInsight for SQL: Expensive Queries Info'  WHEN e.NetObjectType = 'ABTT' THEN 'APM: Windows Scheduled Tasks'  WHEN e.NetObjectType = 'ABXA' THEN 'AppInsight for Exchange: Application'  WHEN e.NetObjectType = 'ABXD' THEN 'AppInsight for Exchange: Database'  WHEN e.NetObjectType = 'ABXDC' THEN 'AppInsight for Exchange: Database Copy'  WHEN e.NetObjectType = 'ABXF' THEN 'AppInsight for Exchange: Database File'  WHEN e.NetObjectType = 'ABXMB' THEN 'AppInsight for Exchange: Mailboxes'  WHEN e.NetObjectType = 'ABXR' THEN 'AppInsight for Exchange: Replication Status'  WHEN e.NetObjectType = 'AM' THEN 'APM: Component'  WHEN e.NetObjectType = 'C' THEN 'Group'  WHEN e.NetObjectType = 'CCM' THEN 'NTA: CBQoS Class Map'  WHEN e.NetObjectType = 'DBI' THEN 'Database Instance'  WHEN e.NetObjectType = 'EWE' THEN 'EnergyWise Entity'  WHEN e.NetObjectType = 'F5' THEN 'F5 Devices'  WHEN e.NetObjectType = 'FCP' THEN 'Fibre Channel Port'  WHEN e.NetObjectType = 'FCR' THEN 'Fibre Channel Revision'  WHEN e.NetObjectType = 'FCS' THEN 'Fibre Channel Sensor'  WHEN e.NetObjectType = 'FCU' THEN 'Fibre Channel Unit'  WHEN e.NetObjectType = 'FN' THEN 'F5 Nodes'  WHEN e.NetObjectType = 'FP' THEN 'F5 Pools'  WHEN e.NetObjectType = 'FVS' THEN 'F5 Virtual Servers'  WHEN e.NetObjectType = 'GM' THEN 'Group Member'  WHEN e.NetObjectType = 'HWH' THEN 'Hardware'  WHEN e.NetObjectType = 'HWHS' THEN 'Hardware Sensor'  WHEN e.NetObjectType = 'HWHT' THEN 'Hardware Type'  WHEN e.NetObjectType = 'I' THEN 'Interface'  WHEN e.NetObjectType = 'IPAM-DSO' THEN 'IPAM DHCPScopes Overlapping'  WHEN e.NetObjectType = 'IPAMG' THEN 'IPAM Networks'  WHEN e.NetObjectType = 'IPAMN' THEN 'IPAM Node or IPAddress Conflict'  WHEN e.NetObjectType = 'ISOP' THEN 'IP SLA QoS'  WHEN e.NetObjectType = 'L' THEN 'Location'  WHEN e.NetObjectType = 'MCG' THEN 'Multicast Routing Group'  WHEN e.NetObjectType = 'MCGN' THEN 'Multicast Routing'  WHEN e.NetObjectType = 'N' THEN 'Node'  WHEN e.NetObjectType = 'NBR' THEN 'Routing Neighbors'  WHEN e.NetObjectType = 'NCH' THEN 'UCS Chassis'  WHEN e.NetObjectType = 'NVLAN' THEN 'VLAN'  WHEN e.NetObjectType = 'NVS' THEN 'VSAN'  WHEN e.NetObjectType = 'NWA' THEN 'Node Warranty'  WHEN e.NetObjectType = 'P' THEN 'VoIP Infrastructure'  WHEN e.NetObjectType = 'T' THEN 'Transaction'  WHEN e.NetObjectType = 'TS' THEN 'Step'  WHEN e.NetObjectType = 'TSR' THEN 'Step Request'  WHEN e.NetObjectType = 'UCSB' THEN 'UCS Blade'  WHEN e.NetObjectType = 'UCSF' THEN 'UCS Fabric'  WHEN e.NetObjectType = 'UCSFAN' THEN 'UCS Fan'  WHEN e.NetObjectType = 'UCSM' THEN 'UCS Manager'  WHEN e.NetObjectType = 'UCSPSU' THEN 'UCS Psu'  WHEN e.NetObjectType = 'UE-DNS' THEN 'UDT: Rogue DNSName or Hostname'  WHEN e.NetObjectType = 'UE-IP' THEN 'UDT: Rogue EmptyDNSName or IPAddress'  WHEN e.NetObjectType = 'UE-MAC' THEN 'New MAC Vendor or Moved, New, Rogue MAC Address'  WHEN e.NetObjectType = 'UNDPI' THEN 'Custom Interface Poller'  WHEN e.NetObjectType = 'UNDPN' THEN 'Custom Node Poller'  WHEN e.NetObjectType = 'UNDPT' THEN 'Custom Node Table Poller'  WHEN e.NetObjectType = 'UP' THEN 'AccessPort'  WHEN e.NetObjectType = 'UW' THEN 'Watch List'  WHEN e.NetObjectType = 'V' THEN 'Volume'  WHEN e.NetObjectType = 'VCCM' THEN 'VoIP CallManager'  WHEN e.NetObjectType = 'VCCMP' THEN 'VoIP Phone'  WHEN e.NetObjectType = 'VCDS' THEN 'VoIP Call Details'  WHEN e.NetObjectType = 'VG' THEN 'VoIP Gateway'  WHEN e.NetObjectType = 'VH' THEN 'Virtual Host'  WHEN e.NetObjectType = 'VMC' THEN 'Virtual Cluster'  WHEN e.NetObjectType = 'VMD' THEN 'Virtual DataCenter'  WHEN e.NetObjectType = 'VMS' THEN 'Virtual Datastore'  WHEN e.NetObjectType = 'VR' THEN 'VoIP Region'  WHEN e.NetObjectType = 'VRF' THEN 'VRF'  WHEN e.NetObjectType = 'VVC' THEN 'Virtual Center'  WHEN e.NetObjectType = 'VVG' THEN 'VoIP PRI Gateway'  WHEN e.NetObjectType = 'VVGT' THEN 'VoIP PRI Trunk'  WHEN e.NetObjectType = 'VVM' THEN 'Virtual Machine'  WHEN e.NetObjectType = 'WLAP' THEN 'Wireless Access Point'  WHEN e.NetObjectType = 'WLC' THEN 'Wireless Controller'  WHEN e.NetObjectType = 'WLHM' THEN 'Wireless Heatmap'  WHEN e.NetObjectType IS NULL AND e.EventMessage LIKE 'IPAM Service%' THEN 'Orion Engine'  WHEN e.NetObjectType IS NULL AND e.EventMessage LIKE '%trap packet%' THEN 'SNMP Trap'  WHEN e.NetObjectType IS NULL AND (e.EventMessage LIKE '%Nightly Maintenance%' OR e.EventMessage LIKE '%database maintenance%') THEN 'Orion Engine'  ELSE 'N/A'  END AS ObjectType,  e.NetObjectValue,  e.NetworkNode,  e.InstanceType,  e.EventTime
FROM  Orion.Events e
JOIN  Orion.EventTypes et ON e.EventType = et.EventType