Find value that is missing from table - sql

Question

I have 3 tables I am using to compare data and find where a record may be missing from one of the tables. The tables are A_Client, A_USER_Defined and A_Group_Member.
A_CLIENT contains: ClientName, ClientUID
A_USER_Defined contains: ClientUID, LOB
A_GROUP_MEMBER contains: ID, ClientUID
So the common column in each is ClientUID.
I am trying to find the Device(s) where defined.lob = 'value1' and does not exist in the member table where member.id = 'value2'
So far my searches comes up empty and am guessing it's something to do with the different joins? Here is the query I am using:
SELECT A_CLIENT.ClientName
, A_CLIENT.ClientUID
, A_USER_DEFINED.LOB
FROM A_CLIENT
INNER JOIN
A_USER_DEFINED ON A_CLIENT.ClientUID = A_USER_DEFINED.ClientUID
WHERE A_USER_DEFINED.LOB = 'value1'
AND NOT EXISTS (
SELECT ClientUID
FROM A_GROUP_MEMBER
WHERE GroupID = 'value2'
)
Any help would be greatly appreciated.
Thank you.

Answer 1

select cli.ClientName, cli.ClientUID, def.LOB
from A_CLIENT cli
inner join A_USER_DEFINED def on def.ClientGUID = cli.ClientGUID and def.LOB = 'value1'
left join A_GROUP_MEMBER grp on grp.ClientUID = cli.ClientUID and mbr.ID = 'value2'
where mbr.UID is null
select cli.ClientName, cli.ClientUID, def.LOB
from A_CLIENT cli, A_USER_DEFINED def
where def.ClientGUID = cli.ClientGUID and def.LOB = 'value1'
and cli.ClientUID not in (select ClientUID from A_GROUP_MEMBER where GroupID = 'value2')
and various other possibilities, depending on what type of join or predicate your engine is more comfortable with
Edit: the question and the table/field names changed considerably since I posted my answer. They seem to have settled down now and so I changed my code to suit.
Note: the EXISTS predicate in your query only checks whether are any records at all with ID = 'value2'; it should quite probably check only for records that also have a matching UID.
Also, there seems to be some confusion potential between ClientUID and ClientGUID. Is that a typo or does your DB actually have both names in it? If it is the latter then someone is in dire need of being educated with a blunt instrument.

Answer 2

select devices.*
from devices
left join member
on devices.ClientUID = member.ClientUID
and devices.lob = 'value1'
and member.id = 'value2'
where member.ClientUID is null

Answer 3

I think you are actually quite close and just need to correlate the not the exists subquery. Without sample data I haven't tested, but I think that minimal correction will fix your query.
SELECT A_CLIENT.ClientName
, A_CLIENT.ClientUID
, A_USER_DEFINED.LOB
FROM A_CLIENT
INNER JOIN
A_USER_DEFINED ON A_CLIENT.ClientUID = A_USER_DEFINED.ClientUID
WHERE A_USER_DEFINED.LOB = 'value1'
AND NOT EXISTS (
SELECT ClientUID
FROM A_GROUP_MEMBER
WHERE A_GROUP_MEMBER.ClientUID = A_CLIENT.ClientUID
AND GroupID = 'value2'
)
I'd probably use some table alias ti make that easier to read but ymmv:
SELECT c.ClientName
, c.ClientUID
, u.LOB
FROM A_CLIENT c
INNER JOIN
A_USER_DEFINED u ON c.ClientUID = u.ClientUID
WHERE A_USER_DEFINED.LOB = 'value1'
AND NOT EXISTS (
SELECT 1
FROM A_GROUP_MEMBER g
WHERE g.ClientUID = c.ClientUID
AND GroupID = 'value2'
)