Does a Self Join or EXISTS Help here? - sql

Question

I'm Using Advantage Server 12.
I need a result set that finds all the records when the supplied parameter occurs in either of a master or a detail table when the supplied value is not the linking field.
Customer Table
|AccountCode |Tel1|Tel2|Tel3|Accout Name/Address etc....
| ACODE | | | |
N < 2
Contact Table
|AccountCode |cTel1|cTel2|cTel3|ContactName/Address etc....
| ACODE | | | |
N >=0
Require the Row from Customer and All rows with matching ACODE from Contacts.
When Tel1 or Tel2 or Tel3 or cTel1 or cTel2 or cTel3 is supplied
This SQL gives the required result when the supplied value ('thenumber') is found in any of the Customer fields
When the supplied number is found in the contact table it returns the Customer fields and only data from the matching row in Contacts
declare #Tel string;
set #Tel = 'thenumber';
select
#TEL as calling,c.Tel1,c.Tel2,c.contact as "Primary",
c.acnt_nmbr,c.Acnt_name, a.contact,a.cTel1 as telephone1,a.cTel2 as telephone2
from
customer c
full outer join contact a on (c.acnt_nmbr=a.acnt_nmbr)
where
replace(c.Tel1,' ','') = #Tel
or
replace(c.Tel2,' ','') = #Tel
or
replace(c.Tel3,' ','') = #Tel
or
replace(a.cTel1,' ','') = #Tel
or
replace(a.cTel2,' ','') = #Tel
or
replace(a.cTel3,' ','') = #Tel
Result when 'thenumber' is found in Customer - This is what we want
calling Tel1 Tel2 Primary acnt_nmbr Acnt_name contact telephone1 telephone2
thenumber 11111111 thenumber KIERAN 687 theCo Pat 12234560 333444555
thenumber 11111111 thenumber KIERAN 687 theco Mary 45678900 444555666
thenumber 11111111 thenumber KIERAN 687 theco Jon 22233344
thenumber 11111111 thenumber KIERAN 687 theco Paul 22244455 124578111
thenumber 11111111 thenumber KIERAN 687 theco Jane 33225544
Result when 'thenumber' is found in Contacts - We want the same result set as above
calling Tel1 Tel2 Primary acnt_nmbr Acnt_name contact telephone1 telephone2
thenumber 11111111 2222222 KIERAN 687 theco Jane thenumber
I'm thinking either some self join or EXISTS statement is the answer but not sure how to proceed.

Answer 1

It's a bit more tricky than you seem to expect and as far as I just see your latest comment, I hope the solution I will propose you will work (I do not know SAP technical environment at all).
On a SQL point of you, my approach is the following.
For both customer and contact, find matching values. It's quite easy for customer, but for contacts you need to identify single matching values, then keep contacts where all values are matching
Then, build the assembly of customer and contacts.
Finally, union results from both first filters, joined with the basis data.
Here is the final request I propose:
with cust_check as (
SELECT account_code, tel1, tel2, tel3, address,
CASE WHEN tel1 = #Tel THEN 1
ELSE CASE WHEN tel2 = #Tel THEN 1
ELSE CASE WHEN tel3 = #Tel THEN 1
ELSE 0
END
END
END as cust_match
from customer
),
cust_filter as (
SELECT account_code, tel1, tel2, tel3, address AS detail
FROM cust_check
WHERE cust_match = 1
),
contact_check as (
SELECT account_code, ctel1, ctel2, ctel3, cname,
CASE WHEN ctel1 = #Tel THEN 1
ELSE CASE WHEN ctel2 = #Tel THEN 1
ELSE CASE WHEN ctel3 = #Tel THEN 1
ELSE 0
END
END
END as contact_match
FROM contact
),
contact_filter as (
SELECT account_code, count(*) as nb_rows, sum(contact_match) as nb_matched
FROM contact_check
GROUP BY account_code
HAVING count(*) = sum(contact_match)
),
all_contacts as (
SELECT t.account_code, ctel1, ctel2, ctel3, cname, address
FROM contact as t
JOIN customer as c ON c.account_code = t.account_code
),
union_match as
(
SELECT c.account_code, c.ctel1, c.ctel2, c.ctel3, c.cname, c.address
FROM all_contacts c
JOIN cust_filter f ON f.account_code = c.account_code
UNION
SELECT c.account_code, c.ctel1, c.ctel2, c.ctel3, c.cname, c.address
FROM all_contacts c
JOIN contact_filter f ON f.account_code = c.account_code
)
SELECT account_code, ctel1, ctel2, ctel3, cname, address
FROM union_match
This request is based on MS SQL Server and you can easily 'play' with it thanks to DB-Fiddle - I just hope it will be compliant with your constraints!

Answer 2

This should achieve what you want:
select
#TEL as calling,c.Tel1,c.Tel2,c.contact as "Primary",
c.acnt_nmbr,c.Acnt_name, a.contact,a.cTel1 as telephone1,a.cTel2 as telephone2
from
customer c
left join contact a on (c.acnt_nmbr=a.acnt_nmbr)
WHERE c.acnt_nmbr IN
(
SELECT DISTINCT acnt_nmbr FROM
(SELECT acnt_nmbr, Tel1, Tel2
FROM Customer
UNION
SELECT acnt_nmbr, cTel1, cTel2
FROM Contact) x
WHERE
replace(x.Tel1,' ','') = #Tel
or
replace(x.Tel2,' ','') = #Tel
)
(I'll leave you to work out how to add the Tel3 :)
Note that I have changed your full outer join to a simple left join because the code as presented will not work with customerless contacts.
If you really need a full outer join, the code becomes a bit more convoluted:
SELECT z.* FROM
( select #TEL as calling,c.Tel1,c.Tel2,c.contact as "Primary",
COALESCE(c.acnt_nmbr,a.acnt_nmbr) AS AccountNo,
c.Acnt_name, a.contact,a.cTel1 as telephone1,a.cTel2 as telephone2
from
Customer c
full outer join Contact a on (c.acnt_nmbr=a.acnt_nmbr)
) z
WHERE COALESCE(z.AccountNo,0) IN
(...)
I have modified Christophe's DB-fiddle to show this working.
Note that the solution for the full outer join is slightly different in the fiddle, to cope with the different behaviour of Microsoft SQL server compared to the Advantage database server. (With ADS DBF tables, NULL values in an integer field become zeros in the UNION for example).