如何在实体框架中为标识列插入值？

Question

I've created two columns in sql table that one is a identity column and another one is a varchar column. I need to generate identity column starting from the value 1000. I had tried the below code snippet, but it was given error "An error occurred while updating the entries. See the inner exception for details.."

   Place objPlace = new Place();
   objPlace.PNAME = "place 3";
   //objPlace.PID = 1003;   //purposefully commented for auto increment

   objContext.Places.AddObject(objPlace);
   objContext.SaveChanges();

I guess this is very basic question as I'm new to EF so please help me to sort it out.

Answer 1

Are you just wanting to do this in EF to learn the syntax? the reason I ask, is because you could set the seed on the column in SSMS ( http://msdn.microsoft.com/en-gb/library/aa933196%28v=sql.80%29.aspx )

Answer 2

You cannot assign value to the Identity column. its meaningless.

if you want to change the starting value of your identity column, why not do it through a simple script?

context.Database
       .ExecuteSqlCommand("ALTER TABLE Place ALTER COLUMN Id IDENTITY (1000,1)");

this will insert Place.Id as 1000, for the first row in the table, and then 1001,1002... and so on for subsequent rows.

Answer 3

Let sql server generate identity. Set values for identity seed and Identity increment.

When column is identity , inserting record from entity framework will raise following error. Cannot insert explicit value for identity column in table 'MY_ENTITY' when IDENTITY_INSERT is set to OFF. To avoid error set entity property StoreGeneratedPattern="Identity"

  <EntityType Name="MY_ENTITY">
              <Key>
                <PropertyRef Name="UserID" />
              </Key>
              <Property Name="RecordID" Type="int" StoreGeneratedPattern="Identity" Nullable="false" />

Answer 4

The ExecuteSqlCommand() command mentioned in above post will not work as mentioned in the link

Aother solution is mentioned the here