Datareader.getfieldtype(55) returned null - error

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Using Windows forms and vb.net

I am experiencing the DataReader.GetFieldType(55) returned null error which is related to missing sql server types.

I cannot reproduce the error from my computer, it only occurs when deployed.

What I have tried:

I have added the sql server types dll to my project as well as the SqlServerTypes folder with x64, x86 and Loader.cs inside.

I have converted the Loader.cs to vb using a link to an answer below.

I've also added this to my app.config:

HTML

<dependentAssembly>
    <assemblyIdentity name="Microsoft.SqlServer.Types" publicKeyToken="00000" culture="neutral" />
    <bindingRedirect oldVersion="0.0.0.0-14.0.0.0" newVersion="14.0.0.0" />
  </dependentAssembly>

Posted 24-Sep-19 6:24am

Member 14476420

Updated 3-Feb-21 23:27pm

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[no name] 24-Sep-19 13:48pm

Get a copy of a database / table that has the issue and test with that. Maybe your database is out of sync / out of date.

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Dave Kreskowiak · Answer 1 · 2019-09-24T06:35:00

Solution 1

If it's returning null, there are two possibilities. First, there is no 55th column in the result set the DataReader is going through.

And 2nd, the returned column does exist, but is defined as a UserDefinedType on the database side. You cannot get the type on the client side for one of these. Your query is going to have to break the user type into a bunch of base fields that hold the appropriate data.

Posted 24-Sep-19 6:35am

Dave Kreskowiak

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Member 14476420 24-Sep-19 12:59pm

running this query on the database: select * from sys.types order by system_type_id asc
I can see that there is no sql server data type 55, so maybe the 2nd part of your answer is the way to go

Dave Kreskowiak 24-Sep-19 15:06pm

There is no such thing as Type 55 in SQL server. You seem to not understand what GetFieldType does. It returns the .NET Framework equivalent type of the database type for the column number in the result set of your SELECT query in your DataReader.

We can't tell you what's wrong because se can't see the failing code and we know nothing about your database design and what your query is supposed to be returning.

Oh, and if you're using SELECT * in your query, you're making a huge mistake.

It does NOT go to the database and attempt to lookup type information for some arbitrary "Type #55".

What you told the code to do was get the .NET type for the 55th column of the result set your SqlDataReader is returning from the database.

OriginalGriff · Answer 2 · 2019-09-24T06:42:00

Solution 2

See here: DataReader.GetFieldType returned null[^]

Posted 24-Sep-19 6:42am

OriginalGriff

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Member 14476420 24-Sep-19 12:52pm

Thanks but as I have explained in my question, I've already tried that