On Sat, 28 Sep 2002 19:20:43 -0400 (EDT), Bruce Momjian
<pgman@candle.pha.pa.us> wrote:
>OK, that is a good example. It would return the sum of the matching
>tags. You are suggesting here that it would be better to take the
>result of the last matching tag command, right?
The examples were meant to support my previous suggestion of
explicitly marking the statement you want to be counted, something
like:
CREATE VIEW twotables ASSELECT ... FROM table1 INNER JOIN table2 ON ... ;
CREATE RULE twotables_insert AS -- INSERT ruleON INSERT TO twotables DO INSTEAD ( COUNT INSERT INTO table1
VALUES(new.pk, new.col1); INSERT INTO table2 VALUES (new.pk, new.col2)); CREATE RULE twotables_update AS --
UPDATEruleON UPDATE TO twotables DO INSTEAD ( COUNT UPDATE table1 SET col1 = new.col1 WHERE pk = old.pk; UPDATE
table2SET col2 = new.col2 WHERE pk = old.pk); CREATE RULE twotables_delete AS -- DELETE ruleON DELETE TO twotables
DOINSTEAD ( COUNT DELETE FROM table1 WHERE pk = old.pk; DELETE FROM table2 WHERE pk = old.pk);
CREATE VIEW visible ASSELECT ... FROM table3WHERE deleted = 0;
CREATE RULE visible_delete AS -- DELETE ruleON DELETE TO visible DO INSTEAD COUNT UPDATE table3 SET deleted
=1 WHERE pk = old.pk;
One argument against automatically "don't count non-INSTEAD rules and
count the last statement in INSTEAD rules": sql-createrule.html says:
| for view updates: there must be an unconditional INSTEAD rule [...]
| If you want to handle all the useful cases in conditional rules, you
| can; just add an unconditional DO INSTEAD NOTHING rule [...]
| Then make the conditional rules non-INSTEAD
CREATE RULE v_update AS -- UPDATE ruleON UPDATE TO v DO INSTEAD NOTHING;
CREATE RULE v_update2 AS -- UPDATE ruleON UPDATE TO v WHERE <condition1>DO ( COUNT ...);
CREATE RULE v_update3 AS -- UPDATE ruleON UPDATE TO v WHERE <condition2>DO ( COUNT ...);
ServusManfred
