Re: SQL Transaction related

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От A. Kretschmer
Тема Re: SQL Transaction related
Дата
Msg-id 20070510065552.GC16765@a-kretschmer.de
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Ответ на SQL Transaction related  ("Harpreet Dhaliwal" <harpreet.dhaliwal01@gmail.com>)
Список pgsql-general
am  Thu, dem 10.05.2007, um  2:24:40 -0400 mailte Harpreet Dhaliwal folgendes:
> Hi,
>
> I have a transaction like following:
>
> BEGIN
>
>      INSERT INTO tbl_xyz VALUES (val1, val2);
>
>     SELECT INTO wid MAX(val1) FROM tbl_xyz;
>
> END;
>
> My question is in the SELECT INTO statement, will I get the value of val1 from
> the INSERT INTO in the same transaction

No, you get MAX(val1). If the last inserted record contains this value,
than you get it.


> even though the transaction has not ended yet.
> I think no.

Within a transaction you see everything that has gone in this
transaction. Why not?


> How would I get that latest value of val1 in the same transaction because its
> not committed yet as the transaction has not ended.

We have MVCC, and you see your own snapshot, including all results
within this transaction.


Andreas
--
Andreas Kretschmer
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