Entity Framework: table without primary key

.net entity-framework
Cris picture Cris · Oct 22, 2010 · Viewed 171.3k times · Source

I have an existing DB with which I would like to build a new app using EF4.0

Some tables do not have primary keys defined so that when I create a new Entity Data Model, I get the following message:

The table/view TABLE_NAME does not have a primary key defined 
and no valid primary key could be inferred. This table/view has 
been excluded. To use the entity, you will need to review your schema, 
add the correct keys, and uncomment it.

If I want to use them and modify data, must I necessarily add a PK to those tables, or is there a workaround so that I don't have to?

Answer

Colin picture Colin · Oct 5, 2011

I think this is solved by Tillito:

Entity Framework and SQL Server View

I'll quote his entry below:

We had the same problem and this is the solution:

To force entity framework to use a column as a primary key, use ISNULL.

To force entity framework not to use a column as a primary key, use NULLIF.

An easy way to apply this is to wrap the select statement of your view in another select.

Example:

SELECT
  ISNULL(MyPrimaryID,-999) MyPrimaryID,
  NULLIF(AnotherProperty,'') AnotherProperty
  FROM ( ... ) AS temp

answered Apr 26 '10 at 17:00 by Tillito

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