Nested Oracle SQL - Multiple Values - sql

Question

I have a table structure like:
Table = contact
Name Emailaddress ID
Bill bill#abc.com 1
James james#abc.com 2
Gill gill#abc.com 3
Table = contactrole
ContactID Role
1 11
1 12
1 13
2 11
2 12
3 12
I want to select the Name and Email address from the first table where the person has Role 12 but not 11 or 13. In this example it should return only Gill.
I believe I need a nested SELECT but having difficulty in doing this. I did the below but obviously it isn't working and returning everything.
SELECT c.Name, c.Emailaddress FROM contact c
WHERE (SELECT count(*) FROM contactrole cr
c.ID = cr.ContactID
AND cr.Role NOT IN (11, 13)
AND cr.Role IN (12)) > 0

Answer 1

You can use a combination of EXISTS and NOT EXISTS
SELECT *
FROM contact c
WHERE
EXISTS(SELECT 1 FROM contactrole cr WHERE cr.ContactID = c.ID AND cr.Role = 12)
AND NOT EXISTS(SELECT 1 FROM contactrole cr WHERE cr.ContactID = c.ID AND cr.Role IN(11, 13))
Another option is to use GROUP BY and HAVING:
SELECT c.*
FROM contact c
INNER JOIN contactrole cr
ON cr.ContactID = c.ID
GROUP BY
c.ID, c.Name, c.Emailaddress
HAVING
SUM(CASE WHEN cr.Role = 12 THEN 1 ELSE 0 END) > 0
AND SUM(CASE WHEN cr.Role IN(11, 13) THEN 1 ELSE 0 END) = 0

Answer 2

Use conditional aggregation in Having clause to filter the records
Try this
SELECT c.NAME,
c.emailaddress
FROM contact c
WHERE id IN (SELECT contactid
FROM contactrole
GROUP BY contactid
HAVING Count(CASE WHEN role = 12 THEN 1 END) > 1
AND Count(CASE WHEN role in (11,13) THEN 1 END) = 0)
If you have only 11,12,13 in role then use can use this
SELECT c.NAME,
c.emailaddress
FROM contact c
WHERE id IN (SELECT contactid
FROM contactrole
GROUP BY contactid
HAVING Count(CASE WHEN role = 12 THEN 1 END) = count(*)

Answer 3

You can do this using JOINs:
SELECT c.*
FROM CONTACT c
INNER JOIN CONTACTROLE cr12
ON cr12.CONTACTID = c.ID AND
cr12.ROLE = 12
LEFT OUTER JOIN CONTACTROLE cr11
ON cr11.CONTACTID = c.ID AND
cr11.ROLE = 11
LEFT OUTER JOIN CONTRACTROLE cr13
ON cr13.CONTACTID = c.ID AND
cr13.ROLE = 13
WHERE cr11.ROLE IS NULL AND
cr13.ROLE IS NULL
The INNER JOIN CONTACTROLE cr12 requires that role 12 exist for the given contact ID; the LEFT OUTER JOIN CONTACTROLE cr11 and LEFT OUTER JOIN CONTRACTROLE cr13 check to see if roles 11 and 13 might exist for the given contact ID; and the WHERE clause verifies that neither roles 11 or 13 exist.
Best of luck.