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I'm running NHibernate and SQL Server CE I am trying to use GUIDs as my ID column. This is the code I already have:

Mapping:

 <class name="DatabaseType" table="DBMON_DATABASE_TYPE"> <id name="Id" column="DATABASE_TYPE_ID"> <generator class="guid" /> </id> <property name="DispName" /> </class>

And this is the create statement it creates:

create table DBMON_DATABASE_TYPE ( DATABASE_TYPE_ID BIGINT not null, DispName NVARCHAR(255) null, primary key (DATABASE_TYPE_ID) )

And this is the kind of insert statement I want to be able to run on it:

Insert into DBMON_DATABASE_TYPE (DATABASE_TYPE_ID,DISPNAME) values ('f5c7181e-e117-4a98-bc06-733638a3a264','DOC')

And this is the error I get when I try that:

Major Error 0x80040E14, Minor Error 26306 > Insert into DBMON_DATABASE_TYPE (DATABASE_TYPE_ID,DISPNAME) values ('f5c7181e-e117-4a98-bc06-733638a3a264','DOC') Data conversion failed. [ OLE DB status value (if known) = 2 ]

Once again my goal is to be able to use GUIDs as the ID column of my table, they don't even need to be auto generated, I can generate them manually in the Save/SaveOrUpdate methods of NHibernate. If there is any other information you need to know please let me know!

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3 Answers 3

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In your mapping you need to identify that you want NHibernate to create a GUID in the database schema (it looks like you are generating your schema from the nhibernate mapping). Off the top of my head the following should work:

<id name="Id" column="DATABASE_TYPE_ID" type="Guid"> <generator class="guid" /> </id>
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instead of

DATABASE_TYPE_ID BIGINT not null,

it needs to be

DATABASE_TYPE_ID UNIQUEIDENTIFIER not null,

I would strongly advice you to use NEWSEQUENTIALID() as a default instead since you are using it as a clustered index because it won't cause page splits and thus fragmentation, see here how to use it http://msdn.microsoft.com/en-us/library/ms189786.aspx

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Use Guid.Comb if generating IDs on the client side. Use NewSequentialID if the database is generating the IDs.
Comb units only work well when a single instance of the clientside is running. You can also assign GUid.NewGuid on the client side when you need run on multiple boxes.
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Dare I recommend using GuidComb's instead?

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