Hi,
I am scratching my head at a neat way of doing an update function for my
db.
-- Here is a sketch schema
CREATE TABLE item ( itemid serial, PRIMARY KEY (itemid)
);
CREATE TABLE property ( propertyid serial, prName text, UNIQUE(prName), PRIMARY KEY(propertyid)
);
CREATE TABLE itemproperty ( itempropertyid serial, ipItemid int REFERENCES item(itemid), ipPropertyid int REFERENCES
property(propertyid),ipValue text, UNIQUE(ipItemid,ipPropertyid), PRIMARY KEY(itempropertyid)
);
-- Sample data
INSERT INTO property (prname) VALUES('name');
INSERT INTO property (prname) VALUES('rank');
INSERT INTO property (prname) VALUES('serial');
INSERT INTO item (itemid) VALUES(nextval('item_itemid_seq'));
INSERT INTO itemproperty (ipItemid,ipPropertyid,ipValue)SELECT currval('item_itemid_seq'),propertyid,'John Wayne'FROM
propertyWHERE prname = 'name';
INSERT INTO itemproperty (ipItemid,ipPropertyid,ipValue)SELECT currval('item_itemid_seq'),propertyid,'XP453-2421'FROM
propertyWHERE prname = 'serial';
I want to write a function that will update itemproperty with a new set
of property name/value pairs.
Any new property name's that appear should be inserted, any old propery
names that no longer appear should be deleted, and any existing values
should be updated.
I am not quite sure where to start.
If I have an update function that takes (int,text,text) as args where $1
is itemid, $2 is a list of comer separated prnames and $3 is a list of
comer separated ipvalues, then I can do the Delete okay, but the insert
and update become difficult.
If I have an update function that takes (int,text[][]) as args where $2
is an array of prname,ipvalue pairs then the update is easy, but the
delete and insert become harder I think.
Which route is more promising?
--
Best Regards
David Stanaway
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