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freetds - RE: [freetds] IDENTITY column problem with bcp

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  • From: "Lowden, James K" <LowdenJK AT bernstein.com>
  • To: "'FreeTDS Development Group'" <freetds AT lists.ibiblio.org>
  • Subject: RE: [freetds] IDENTITY column problem with bcp
  • Date: Wed, 23 Apr 2003 12:56:46 -0400

> From: Thompson, Bill D (London) [mailto:ThompBil AT exchange.uk.ml.com]
> Sent: April 23, 2003 10:50 AM
>
> >From this, I suspect what happens is if there is an identity
> column in the
> table (we can know this from the initial describing select we
> do from the
> table in bcp_init()), then the bcp program uses the functions
> IDENT_SEED and
> IDENT_INCR to work out values and manually assigns the values into the
> "rows" it sends to the server.

Huh. You must be right, because there's no option in db-lib bcp API
affecting Identity columns. Nor even mention, afaict. I had read that
"... Server generates ..." description before and assumed it was something
in the protocol.

Sybase's db-lib also doesn't mention Identity columns. ct-lib does; an
application can send zeros to the server, and it will generate appropriate
values. Cf. blk_props() and BLK_IDENTITY.

With Sybase, if the server is to accept identity values, the client must
first tell the serrver to set identity_insert on. Otherwise, the client is
expected to send zeros and let the server do the work. That might work with
Microsoft, too; we'd obviously have to experiment.

BTW, when Microsoft's bcp prepares to load data, it discovers the table
format by sending a query like this:

SET FORMAT ONLY ON
select * from <dbname>..<tablename>
SET FORMAT ONLY OFF

all as one string, no newlines, just spaces. Because Sybase has no such
option, I doubt we'd ever want to change freebcp's query formulation, but it
seemed worth noting.

Regards,

--jkl


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