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Editorial Team
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Asked: 2026-05-21T15:07:39+00:00

I have the following table: CREATE TABLE [dbo].[MyTable]( [timestamp] [timestamp] NOT NULL, [Col1] [varchar](20)

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I have the following table:

CREATE TABLE [dbo].[MyTable](
    [timestamp] [timestamp] NOT NULL,
    [Col1] [varchar](20) NOT NULL,
    [Col2] [varchar](20) NOT NULL,
    [col3] [datetime] NOT NULL,
    [col4] [varchar](10) NOT NULL,
    [Col5] [varchar](10) NOT NULL,
    [Col6] [varchar](10) NOT NULL,
    [Col7] [decimal](38, 20) NOT NULL,
    [Col8] [decimal](38, 20) NOT NULL,
    [Col9] [datetime] NOT NULL,
 CONSTRAINT [MyTable$0] PRIMARY KEY CLUSTERED 
(
    [Col1] ASC,
    [Col2] ASC,
    [Col3] ASC,
    [Col4] ASC,
    [Col5] ASC,
    [Col6] ASC,
    [Col7] ASC
) WITH (PAD_INDEX  = OFF, STATISTICS_NORECOMPUTE  = OFF, IGNORE_DUP_KEY = OFF, ALLOW_ROW_LOCKS  = ON, ALLOW_PAGE_LOCKS  = ON, FILLFACTOR = 90) ON [Data Filegroup 1]
) ON [Data Filegroup 1]

I use the EF Generator to clreate the MyTable class, set all the fields and save changes. I get the following error:

Store-generated keys are only
supported for identity columns. Key
column ‘Col2’ has type
‘SqlServer.varchar’, which is not a
valid type for an identity column.

What I don’t understand is why it thinks it is an identity column. How would I fix that error? Am I looking in the right direction?

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1 Answer

  1. Editorial Team

    The problem seems to be that the error message is irrelevant. What it should say is something about non-nullable PK values. It seems that one of the values involved in the PK was null. I think this problem has to do with the String type in C# being nullable, since Nullable was set to False in the EF Designer and did not throw an error since it was simply not being set.

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