Re: Bulk loading/merging

On 5/30/06, Jim C. Nasby <jnasby(at)pervasive(dot)com> wrote:

> Your best bet is to do this as a single, bulk operation if possible.
> That way you can simply do an UPDATE ... WHERE EXISTS followed by an
> INSERT ... SELECT ... WHERE NOT EXISTS.

hmm, I don't quite understand what you are saying and I think my
basic misunderstanding is how to use the UPDATE ... WHERE EXISTS to merge
data in bulk. Assuming that I bulk COPYed the data into a temporary
table, I'd need to issue an UPDATE for each row in the newly created table,
right?

For example, for a slightly different key,count schema:

CREATE TABLE kc (key integer, count integer);

and wanting to merge the following data by just updating the count for a
given key to the equivalent of OLD.count + NEW.count:

1,10
2,15
3,45
1,30

How would I go about using UPDATE ... WHERE EXISTS to update the "master" kc
table from a (temporary) table loaded with the above data?