diff --git a/doc/src/sgml/plpgsql.sgml b/doc/src/sgml/plpgsql.sgml index 9cb0ad2a8b..0d359b1d3b 100644 --- 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'); + + + +