sql query select on two criteria, same field?

I want an sql SELECT that will select on the same field
and will use two, separate criteria for that field.

The result should be the subset that satisfies BOTH criteria.

The example below does not work.

How do I do this?


select * from cam where cust='1' and cust='2'

Open in new window

pillmillAsked:
Who is Participating?
I wear a lot of hats...

"The solutions and answers provided on Experts Exchange have been extremely helpful to me over the last few years. I wear a lot of hats - Developer, Database Administrator, Help Desk, etc., so I know a lot of things but not a lot about one thing. Experts Exchange gives me answers from people who do know a lot about one thing, in a easy to use platform." -Todd S.

Aneesh RetnakaranDatabase AdministratorCommented:
select * from cam where cust='1' or  cust='2'
0
Aneesh RetnakaranDatabase AdministratorCommented:
you never can 1 = 2
0
mrjoltcolaCommented:
You can also use IN()

where cust in('1', '2')
0
Big Business Goals? Which KPIs Will Help You

The most successful MSPs rely on metrics – known as key performance indicators (KPIs) – for making informed decisions that help their businesses thrive, rather than just survive. This eBook provides an overview of the most important KPIs used by top MSPs.

pillmillAuthor Commented:
Thanks. Both where cust in('1', '2')  and  select * from cam where cust='1' or  cust='2'  are producing the WRONG result.

I want the intersection of the sets of results produced by these two queries:

1. select * from cam where cust='1'

2. select * from cam where cust='2'
0
Kent OlsenDBACommented:
Hi pillmill,

The intersection will be a NULL set.  "cust" can be 1, or it can be 2, but it can't be both.


Kent
0
pillmillAuthor Commented:
Thanks. Here are the records:

table cam:

cust     cama
1          a
1           b
2          a
2          c


I want the query to return the value "a" .  The value "a" is the one
which is the same between cust 1 and 2.
0
Kent OlsenDBACommented:

Hmm....  There are a lot of variables here.  Can 'a occur more than once per customer number?  Will it occur only twice?  Are more values than 1 and 2 possible for cust, etc.

Here's one solution:

SELECT cama, count() as c FROM mytable
GROUP BY cama
HAVING c > 1;


Kent
0
AndytwCommented:
Try:
SELECT cama FROM cam WHERE cust = 1
INTERSECT
SELECT cama FROM cam WHERE cust = 2;
 
or
 
SELECT cama c1
FROM cam WHERE cust = 1
WHERE EXISTS ( SELECT NULL
               FROM cam c2
               WHERE c1.cama = c2.cama
                 AND c1.cust <> c2.cust )
  

Open in new window

0
awking00Information Technology SpecialistCommented:
I suspect your problem may be little more complex than that indicated by your example. Are you trying to find values that exist for more than one customer, that exist for every customer, or do you want entire records (or perhaps more than one field) where those instances occur? Perhaps you could post some more relevant sample data and what your expected output should be.
0
pillmillAuthor Commented:
SELECT cama c1
FROM cam WHERE cust = 1
WHERE EXISTS ( SELECT NULL
               FROM cam c2
               WHERE c1.cama = c2.cama
                 AND c1.cust <> c2.cust )

produces a MySQL error:

Error Code : 1064
You have an error in your SQL syntax; check the manual that corresponds to your MySQL server version for the right syntax to use near 'WHERE exists ( SELECT NULL
0
pillmillAuthor Commented:
Record "a" is the common element.  

0
awking00Information Technology SpecialistCommented:
Change "where exists" to "and exists".
0
Kent OlsenDBACommented:
Hi Pill,

In this simple example, the cleanest SQL is an inner join.

SELECT cama
FROM mytable t0, mytable t1
WHERE t0.cama = t1.cama
  AND t0.cust = 1
  AND t0.cust = 2;

But that's probably not a lot of use with a larger data set.  Still, let's see where this goes.  :)


Kent
0

Experts Exchange Solution brought to you by

Your issues matter to us.

Facing a tech roadblock? Get the help and guidance you need from experienced professionals who care. Ask your question anytime, anywhere, with no hassle.

Start your 7-day free trial
kbacCommented:
select * from cam where
cama in (select cama from cam where cust='1' )
and
cama in (select cama from cam where cust='2' )
0
pillmillAuthor Commented:
Thanks!
0
Kent OlsenDBACommented:
Hi Pill,

For the record, there was a typo in my SQL, but it looks like you figured that out.   :)

Kent
0
It's more than this solution.Get answers and train to solve all your tech problems - anytime, anywhere.Try it for free Edge Out The Competitionfor your dream job with proven skills and certifications.Get started today Stand Outas the employee with proven skills.Start learning today for free Move Your Career Forwardwith certification training in the latest technologies.Start your trial today
Oracle Database

From novice to tech pro — start learning today.