SQL DISTINCT WITH JOIN

Does the following return non-unique records?
select org_id, f_name, lname, email_1
from dbo.p_contacts;

Hi there,

No it will not return unique records I am trying out a row over partition method at the moment which would identify duplicate records based on the fields I would declare as uniqe

row_number() OVER(PARTITION BY e.email_1,e.full_name ORDER BY email_1) rn

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This works but I don't know where to put it in my original query, this is what I have done now but don't know where to put my where clause to filter rn = 1

SELECT        f.customer_ID, e.f_name, e.l_name, e.f_name + ' ' + e.l_name AS full_name_p, NULL AS JobTitle, e.tel_1, e.tel_2, e.mobile_1, e.email_1, e.email_2, 
                         5 AS TypeID, 'Auto added Test' AS Note, GETDATE() AS CreatedDate, 0 AS IsInvoice, NULL AS Photo, 0 AS IsAcc, 0 AS IsPrimary,row_number() OVER(PARTITION BY e.email_1,e.full_name ORDER BY email_1) rn
FROM            dbo.p_companies AS f RIGHT OUTER JOIN
                         dbo.p_contacts AS e ON f.id = e.org_id
WHERE       (f.customer_ID =36) AND (e.f_name NOT LIKE 'Customer') AND (e.email_1 IS NOT NULL) AND (e.email_1 <> '') AND (e.f_name IS NOT NULL) AND (NOT EXISTS
                             (SELECT        contact_ID, customer_ID, contact_first_name, contact_last_name, contact_full_name, contact_job_title, contact_tel1, contact_tel2, contact_mobile, 
                                                         contact_mail, contact_alt_mail, contact_type_ID, contact_note, contact_created_date, contact_is_invoice, contact_photo, contact_is_primary, 
                                                         contact_is_acc
                               FROM            dbo.tblContacts
                               WHERE        (contact_mail = e.email_1) AND (contact_full_name = e.f_name + ' ' + e.l_name)));

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Ok I think I figured it out this is what I did, please let me know if you have a better way, however this is working

SELECT        f.customer_ID, e.f_name, e.l_name, e.f_name + ' ' + e.l_name AS full_name_p, NULL AS JobTitle, e.tel_1, e.tel_2, e.mobile_1, e.email_1, e.email_2, 
                         5 AS TypeID, 'Auto added Test' AS Note, GETDATE() AS CreatedDate, 0 AS IsInvoice, NULL AS Photo, 0 AS IsAcc, 0 AS IsPrimary,e.rn
FROM            dbo.p_companies AS f RIGHT OUTER JOIN
                         (SELECT *,row_number() OVER(PARTITION BY email_1,full_name ORDER BY email_1) rn FROM dbo.p_contacts) AS e ON f.id = e.org_id
WHERE      (rn =1) AND (f.customer_ID =36) AND (e.f_name NOT LIKE 'Customer') AND (e.email_1 IS NOT NULL) AND (e.email_1 <> '') AND (e.f_name IS NOT NULL) AND (NOT EXISTS
                             (SELECT        contact_ID, customer_ID, contact_first_name, contact_last_name, contact_full_name, contact_job_title, contact_tel1, contact_tel2, contact_mobile, 
                                                         contact_mail, contact_alt_mail, contact_type_ID, contact_note, contact_created_date, contact_is_invoice, contact_photo, contact_is_primary, 
                                                         contact_is_acc
                               FROM            dbo.tblContacts
                               WHERE        (contact_mail = e.email_1) AND (contact_full_name = e.f_name + ' ' + e.l_name)));

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please read up this article that explains the "issue" in general, and shows the path to success:
https://www.experts-exchange.com/Database/Miscellaneous/A_3203-DISTINCT-vs-GROUP-BY-and-why-does-it-not-work-for-my-query.html

why don't you use a group by clause ?

Hi there, could you show me how to do that because my group by clause still bring duplicate values. BEcause my full_name and email_1 field names need to be distinct within the org_id column?

No idea, how to do that?

Because I need to return all the rows from the p_contacts table so that I can insert them into my tblContacts table. I have tried sub queries the lot but I can't figure this out. GROUP BY won't enable me to return all fields from p_contacts table would it or.....?????

you can use group by in a subquery, but most often it's not the right thing.
my article shows exactly how to do this, by adding a "ROW_NUMBER() OVER (PARTITION BY ID ORDER BY ...) rn  " into the subquery, and adding a RN = 1 into the joining condition.

I have used the row_number over partition as in my earlier code ID: 39999121 but the problem with that is it won't work with my dataset in visual studio as it says the over function is not supported even though I am using sql server 2012.

Hi there i solved the problem using a view instead. Many thanks for all of your help guys.

Very good help