How to select SQL Server 2008 uniqueidentifier and put it in a .net Guid variable?

Question

I am having trouble SELECTing a column of type uniqueidentifier and putting it in a variable of type Guid in ASP.net.

The database is generating the uniqueidentifier, and all I want to do is pull them out and store the values in case I need to populate a foreign key table.

I am using a private member to store the value:

Private _uniqueID as guid

I SELECT from the table and use a SqlDataReader called vRdr. All the other values are coming out just fine, but when I add this I get an error:

if not isDBNull( vRdr("uniqueID")) then _uniqueID = vRdr.GetGuid("uniqueID") end if

The error I get is

Input string was not in a correct format.

I am not sure why I am having so much trouble trying to select these values. I have also tried Guid.Parse() and Guid.TryParse() on the data reader value with no luck.

Thanks for reading.

mgnoonan · Accepted Answer · 2012-04-03 14:42:11Z

3

According to the MSDN docs, GetGuid() takes a column ordinal, not a string key. Change your code to this:

_uniqueID = vRdr.GetGuid(vRdr.GetOrdinal("uniqueID"))

answered Apr 3, 2012 at 14:42

mgnoonan

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2 Comments

rg89 Over a year ago

Awe, that's the sort of learning that doesn't scale well beyond RTFM. Thank you, this works.

mgnoonan Over a year ago

Post your code and any errors as a new question, and we can take a look at resolving the issue.

Khan · Accepted Answer · 2012-04-03 14:42:25Z

1

Have you tried creating a new Guid from your database value?

Example:

_uniqueID = New Guid(vRdr("uniqueID").ToString())

answered Apr 3, 2012 at 14:42

Khan

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2 Comments

rg89 Over a year ago

I had tried new Guid( "" & vRdr("uniqueID")) but not .ToString( ). Your code works, but another correct answer was first. I don't think I can check both.

Khan Over a year ago

I agree mgnoonan's answer is a better solution. Glad to help :)

Stealth Rabbi · Accepted Answer · 2012-04-04 12:50:17Z

If you're calling GetOrdinal() in a loop (for X records in a result set), this can be very costly. You'd want to save off the value of GetOrdinal() once and reuse.

Or, you can use the [] operator on IDataReader and index in given the string identifier for your column. This return an object, but simply cast it to a Guid. Note that indexing by string also calls GetOrdinal, at least in SqlDataReader.

Guid myGuid = (Guid)vRdr["uniqueID"];

Iwuala M. C · Accepted Answer · 2013-08-03 13:58:05Z

often times many procedures works out for many versions of .net framework. Below is the two solutions that actually worked for me visual studio 2012.

ViewState("Guid variable") = ("Guid value")
Dim myGuid As Guid myGuid = ("Guid value")

The first solution retains the variable data after page postback while the second does not. Enjoy!

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