Hi,

Not sure if query syntax is germane here. If not please advise as to
a group where I could ask.

I need to do a kind of join that I have not had to do before. I need
to find records which exist only in one of two tables.

Everyone has a record in `person` but not every person record has an
attendant `contest_entry` record. I need to find records that exist
in `person` but not in `contest_entry`.

So I tried

SELECT person.id, contest_entry.person
FROM person, contest_entry
WHERE person.datetime_added > '2007-11-27'
AND person.id != contest_entry.person

which got me 81,174,327 results as a factorial of the two sets. Who
do I make this negative join?

TIA!!

jg

jerrygarciuh wrote:
> Hi,
>
> Not sure if query syntax is germane here. If not please advise as to
> a group where I could ask.
>
> I need to do a kind of join that I have not had to do before. I need
> to find records which exist only in one of two tables.
>
> Everyone has a record in `person` but not every person record has an
> attendant `contest_entry` record. I need to find records that exist
> in `person` but not in `contest_entry`.
>
> So I tried
>
> SELECT person.id, contest_entry.person
> FROM person, contest_entry
> WHERE person.datetime_added > '2007-11-27'
> AND person.id != contest_entry.person
>
> which got me 81,174,327 results as a factorial of the two sets. Who
> do I make this negative join?
>
> TIA!!
>
> jg

SELECT
person.id,
contest_entry.person
FROM person
LEFT JOIN contest_entry ON person.id = contest_entry.person
WHERE person.datetime_added > '2007-11-27'
AND contest_entry.person IS NULL

Thank you!!! The next time you are in New Orleans I owe you a beer!