> >Luckily, PG 8 is available for this. Do you have a short example?

>
> No, and I think it should be in the manual as an example.
>
> You will need to enter a loop that uses exception handling to detect
> unique_violation.

Pursuant to an IRC discussion to which Dennis Bjorklund and
Christopher Kings-Lynne made most of the contributions, please find
enclosed an example patch demonstrating an UPSERT-like capability.

David Fetter

diff --git a/doc/src/sgml/plpgsql.sgml b/doc/src/sgml/plpgsql.sgml
index 9cb0ad2a8b07864b44c5cc8f1831db4e8a085776..0d359b1d3b3d0364fb0a6950419501e4b96265a5 100644 (file)
--- a/doc/src/sgml/plpgsql.sgml
+++ b/doc/src/sgml/plpgsql.sgml
@@ -1,5 +1,5 @@
 
 
  
@@ -2103,6 +2103,40 @@ END;
       don't use EXCEPTION without need.
      
     
+    
+    
+    This example uses an EXCEPTION to UPDATE or
+    INSERT, as appropriate.
+
+
+CREATE TABLE db (a INT PRIMARY KEY, b TEXT);
+
+CREATE FUNCTION merge_db (key INT, data TEXT) RETURNS VOID AS
+$$
+BEGIN
+    LOOP
+        UPDATE db SET b = data WHERE a = key;
+        IF found THEN
+            RETURN;
+        END IF;
+
+        BEGIN
+            INSERT INTO db(a,b) VALUES (key, data);
+            RETURN;
+        EXCEPTION WHEN unique_violation THEN
+            -- do nothing
+        END;
+    END LOOP;
+END;
+$$
+LANGUAGE plpgsql;
+
+SELECT merge_db (1, 'david');
+SELECT merge_db (1, 'dennis');
+
+
+    
+