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Included is an example of using savepoints in a non-trivial example.

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Giving examples in the SQL command reference is hard because we don't
have conditionals at the SQL level.

Gavin Sherry
This commit is contained in:
Bruce Momjian 2004-08-08 01:48:31 +00:00
parent 51fa8b0120
commit ff8d68df5c
2 changed files with 18 additions and 2 deletions
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5
doc/src/sgml/ref/begin.sgml
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@ -1,5 +1,5 @@
<!--
$PostgreSQL: pgsql/doc/src/sgml/ref/begin.sgml,v 1.31 2004/08/01 17:32:13 tgl Exp $
$PostgreSQL: pgsql/doc/src/sgml/ref/begin.sgml,v 1.32 2004/08/08 01:48:31 momjian Exp $
PostgreSQL documentation
-->
@ -100,6 +100,9 @@ BEGIN [ WORK | TRANSACTION ]
<para>
Issuing <command>BEGIN</> when already inside a transaction block will
provoke a warning message. The state of the transaction is not affected.
To nest transactions within a transaction block, use savepoints
(See <xref linkend="sql-start-transaction" endterm="sql-start-transaction-title">
for more information).
</para>
</refsect1>

15
doc/src/sgml/ref/update.sgml
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@ -1,5 +1,5 @@
<!--
$PostgreSQL: pgsql/doc/src/sgml/ref/update.sgml,v 1.29 2004/06/09 19:08:13 tgl Exp $
$PostgreSQL: pgsql/doc/src/sgml/ref/update.sgml,v 1.30 2004/08/08 01:48:31 momjian Exp $
PostgreSQL documentation
-->
@ -187,6 +187,19 @@ UPDATE employees SET sales_count = sales_count + 1 FROM accounts
<programlisting>
UPDATE employees SET sales_count = sales_count + 1 WHERE id =
(SELECT sales_person FROM accounts WHERE name = 'Acme Corporation');
</programlisting>
Attempt to insert a new stock item along with the quantity of stock. If
the item exists, update the stock count of the existing item. To do this,
use savepoints.
<programlisting>
BEGIN;
SAVEPOINT sp1;
INSERT INTO wines VALUES('Chateau Lafite 2003', '24');
-- Check for unique violation on name
ROLLBACK TO sp1;
UPDATE wines SET stock = stock + 24 WHERE winename='Chateau Lafite 2003';
COMMIT;
</programlisting>
</para>
</refsect1>