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

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

Gavin Sherry

diff --git a/doc/src/sgml/ref/begin.sgml b/doc/src/sgml/ref/begin.sgml
index d40cb416bc51129bbf6774102e9e297eccd94688..bf1195f52772882fbf4845f3c0d2fa39bdfa88fb 100644 (file)
--- a/doc/src/sgml/ref/begin.sgml
+++ b/doc/src/sgml/ref/begin.sgml
@@ -1,5 +1,5 @@
 
 
@@ -100,6 +100,9 @@ BEGIN [ WORK | TRANSACTION ]
   
    Issuing 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 
+   for more information).
   
  
 

diff --git a/doc/src/sgml/ref/update.sgml b/doc/src/sgml/ref/update.sgml
index 5695df1584bbbce2847af6ab28333273a31d4037..48d160b2ece5008f445144735b4b789442e50bcd 100644 (file)
--- a/doc/src/sgml/ref/update.sgml
+++ b/doc/src/sgml/ref/update.sgml
@@ -1,5 +1,5 @@
 
 
@@ -187,6 +187,19 @@ UPDATE employees SET sales_count = sales_count + 1 FROM accounts
 
 UPDATE employees SET sales_count = sales_count + 1 WHERE id =
   (SELECT sales_person FROM accounts WHERE name = 'Acme Corporation');
+
+
+   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.
+
+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;