Retrieving specific data from SQL server Stored procedure - sql-server

Question

The two tables I am using are
Contacts (Contact_id, Contact_name,...)
Contacts_group_options (Contact_id, Group_id, Status)
I want to get all the contacts that are not part of a specific group from the Contacts_group_options table .
The problem is, if first table has Contact_ids 1, 2, 3, 4 and second table has Contact_ids 2, 3 for a Group_id = 1, I want result as 1 and 4. But I am getting 1, 3, 4, 1, 2, 4.
First 1 is compared with 2. Both are not same. Output 1, then 2 with 2 same so don't output, 3 with 2 output 3, 4 with 2 output 4,1 with 3 output 1,2 with 3, output 2,3 with 3 dont output,4 with 3 output 4.
stored procedure is:
Select
m.Contact_id,
m.Contact_code,
m.Contact_name,
m.Phone_number,
m.Mail_id,
m.Designation,
m.Department,
m.User_id,
m.User_type,
m.Status
from
Contacts as m,
Contact_group_options as b
,#tblType_contacts2group as i
where
b.Group_id = i.Group_id
and m.Contact_id != b.Contact_id

Answer 1

I think you can do this with a simple NOT EXISTS:
SELECT c.*
FROM Contacts AS c
WHERE
NOT EXISTS(
SELECT 1
FROM Contact_group_options
WHERE
Group_id = 1
AND Contact_id = c.Contact_id
)

Answer 2

You can try this:
-- NOT EXISTS
SELECT C.*
FROM Contacts C
WHERE NOT EXISTS (SELECT 1 FROM Contacts_group_options WHERE Group_id = 1 AND C.Contact_id)
-- NOT IN
SELECT *
FROM Contacts
WHERE Contact_id NOT IN (SELECT Contact_id FROM Contacts_group_options WHERE Group_id = 1)

Answer 3

Your result set includes so many rows because you actually have three tables there: Contacts, Contact_group_options and #tblType_contacts2group.
Maybe you wanted to write something like this:
-- compacted for to make it more readable
Select
m.Contact_id, m.Contact_code, m.Contact_name, m.Phone_number,
m.Mail_id, m.Designation, m.Department, m.User_id, m.User_type, m.Status
from Contacts as m
where not exists (select 1 from #tblType_contacts2group as i where i.Group_id = m.Group_id)
NOTE: Since #tblType_contacts2group is not clearly defined in your example, above query might not get the correct results.
As already Felix mentioned, you should always use proper joins. E.g. the above query could be like this:
Select
m.Contact_id, m.Contact_code, m.Contact_name, m.Phone_number,
m.Mail_id, m.Designation, m.Department, m.User_id, m.User_type, m.Status
from Contacts as m
left join #tblType_contacts2group i on i.Group_id = m.Group_id
where i.Group_id IS NULL -- any non-null column from i can be used here
However, keep in mind that, usually, LEFT JOIN with IS NULL is slower that NOT EXISTS equivalent.