RiggsHill Software

So how does one use identity keys (a.k.a AutoIncrement IDs) with Entities? It's simple. Really. Just not quite what I expected. Assume this table:

CREATE TABLE svar (
	id INTEGER PRIMARY KEY NOT NULL, 
	name NVARCHAR(32) DEFAULT NULL,
);

Simple. Inserting a record should increment the id field ensuring that it's always unique. But the Entities thing has no provisions for this - or does it? It's not in the GUI (yet?), you have to edit the XML (.edmx) directly, adding an attribute to the column definition:

StorageGeneratedPattern="Identity"

This informs the EF system that the column is generated on insert and that it's to read back the value immediately after an insert - which it appears to do.

StorageGeneratedPattern="Computed"

This tells the EF system that the column is computed on update (or insert) and is to be read back immediately after an update,

StorageGeneratedPattern="None"

The default case - do nothing.

So, for the above table, modify the .edmx file like below (in the SSDL section):

        <EntityType Name="svar">
          <Key>
            <PropertyRef Name="id" />
          </Key>
          <Property Name="id" Type="integer" Nullable="false" StoreGeneratedPattern="Identity" />
          <Property Name="name" Type="nvarchar" MaxLength="32" />