SQL : Record Existance Check in another table - mysql

Question

My requirement is below .
I have two tables let's call them Table A and Table B :
PARTNER_ID PARTNER_Registration Partner_PANNUMBER
----------
1 11 AB1
2 22 AB2
3 33 AB3
4 44 AB4
5 55 AB5
6 66 AB6
7 77 AB5
8 88 AB8
i Will have another table B which contains PID , Preg, Ppan as follows
PID PREG PPAN
----------
1 11 AB1
2 22 AB2
3 33 AB3
4 44
5 AB5
66 AB6
Now I should create a column Output in table A and have output as follows
PARTNER_ID PARTNER_Registration Partner_PANNUMBER Output
----------
1 11 AB1 All three Found
2 22 AB2 All three Found
3 33 AB3 All three found
4 44 AB4 PPAN NOT FOUND
5 55 AB5 PARTNER_Registration Not Found in TABLE B
6 66 AB6 PARTNER_ID Not found in Table B
7 77 AB5 PARTNER_ID, PARTNER_Registration Not found in Table B
8 88 AB8 None of them Found in Table B
Can some one help me find an easy way to acheive this in SQL,
I would like to populate which values of 3 columns are not present in another and update output column accordingly..
Thanks

Answer 1

I would just add up the number of matches:
select a.*,
( exists (select 1 from b where b.PID = a.PARTNER_ID) +
exists (select 1 from b where b.PREG = a.PARTNER_Registration) +
exists (select 1 from b where b.PPAN = a.Partner_PANNUMBER)
) as num_matches
from a;

Answer 2

You can use multiple LEFT JOIN with table B, and test which ones produce NULL values.
SELECT a.*,
CASE WHEN b1.pid IS NOT NULL AND b2.preg IS NOT NULL AND b3.ppan IS NOT NULL
THEN 'All three found'
WHEN b1.pid IS NULL AND b2.preg IS NULL AND p3.ppan IS NULL
THEN 'None of them found in Table B'
ELSE CONCAT(CONCAT_WS(', '
IF(b1.pid IS NULL, 'Partner_ID', NULL),
IF(b2.preg IS NULL, 'Partner_Registration', NULL),
IF(b3.ppan IS NULL, 'PPAN', NULL)),
' not found in Table B') AS Output
FROM TableA AS a
LEFT JOIN TableB AS b1 ON a.partner_id = b1.pid
LEFT JOIN TableB AS b2 ON a.partner_registration = b2.preg
LEFT JOIN TableB AS b3 ON a.partner_pannumber = b.ppan
CONCAT_WS() will ignore null values, so with the IF statements inverting NULL with the names of the missing values, you get the list of results you want.

Answer 3

I would use multiple LEFT JOIN because of the use case of OP where we can manipulate the null values means missing in table2 to achieve the exact output you want.
The query looks big but it is just manipulating the string using specific string functions to get the final string output.
select a.partner_id
,a.partner_registration
,a.partner_pannumber
,case
when chk = ''
then 'All three found'
else
concat(case (length(chk) - length(replace(chk,',','')))
when 3
then 'None of them found'
when 1
then replace(chk,',',' not found')
else
regexp_replace(chk,'[,]',' not found',1,2)
end
,' in table2'
)
end Remarks
from
(
select a.*
,concat(case when pi.pid is null then 'Partner Id,' else '' end
,case when pr.preg is null then 'Partner Registration,' else '' end
,case when pp.ppan is null then 'PPAN,' else '' end
) chk
from table1 a
left join table2 pi
on a.partner_id = pi.pid
left join table2 pr
on a.partner_registration = pr.preg
left join table2 pp
on a.partner_pannumber = pp.ppan
) a
P.S. I personally like the answer with usage of concat_ws as it has less code but you need a little modification for non of them match in ... case.