Re: Novice MySQL Query

On 9 May, 11:54, Rik Wasmus <luiheidsgoe...@hotmail.com> wrote:
> superman183 wrote:
> > Hoping someone can assist me with a query I have.
>
> > I have two tables, both of which have at least one field of the same
> > name, type, etc, etc. This field I will call SKEY, for the purposes of
> > this post. SKEY is a CHAR field, 4 chars in length.
>
> > One of the tables, we'll say Table1, has the complete list of
> > available SKEY's. Table2, on the other hand, contains only some of the
> > available SKEY's.
>
> > I want to be able to find out which SKEY's are missing from Table2;
> > ie. which SKEY's are in Table1, but not in Table2.
>
> > I have tried several different queries, but generally end up in a bit
> > of a mess, more often returning tens of thousands of results, when in
> > fact there are only a couple of hundred records in total.
>
> > My pseudo-code would be something like:
>
> > SELECT SKEY FROM TABLE1 WHERE TABLE1.SKEY NOT LIKE TABLE2.SKEY
>
> > The basic query which I tried is:
>
> > SELECT TABLE1.SKEY FROM TABLE1 JOIN TABLE2 WHERE TABLE1.SKEY NOT LIKE
> > TABLE2.SKEY
>
> > I also tried a few variations, with DISTINCT, etc, etc ... but I never
> > end up with anything close to what I need.
>
> If SKEY in TABLE2 cannot be null.
>
> SELECT TABLE1.SKEY FROM TABLE1
> LEFT JOIN TABLE2 ON TABLE2.SKEY = TABLE1.SKEY
> WHERE TABLE2,SKEY IS NULL;
> --
> Rik Wasmus
> [SPAM]
> Now looking for some smaller projects to work on to fund a bigger one
> with delayed pay. If interested, mail rik at rwasmus.nl
> [/SPAM]
SELECT TABLE1.SKEY FROM TABLE1
LEFT JOIN TABLE2 ON TABLE2.SKEY = TABLE1.SKEY
WHERE TABLE2.SKEY IS NULL;

(replaced comma with full stop)