How to join this query based on condition? - sql

Question

I have a query like below to join 6 table.
select usr.userid,usr.firstName,usr.middleName,usr.lastName,nuser.GRAND_FATHER_NAME,nco untry.NAME_AR,ncountry.NAME_EN,ncase.START_DATE
from User_ usr
inner join TBL_NAFETHAH_USER nuser
On nuser.USER_ID = usr.userId
inner join TBL_NAFETHAH_COUNTRY ncountry
on nuser.NATIONALITY = ncountry.ID
inner join TBL_NAFETHAH_CASE ncase
on usr.userId = ncase.inmate_id
inner join TBL_NAFETHAH_CASE_STATUS ncasestatus
ON ncase.CASE_STATUS_ID = ncasestatus.CASE_STATUS_ID
and ncasestatus.CASE_STATUS IN (1,2))
inner join TBL_NAFETHAH_CASE_STAGE ncasestage
on ncasestage.CASE_STAGE_ID = ncase.CASE_STAGE_ID
inner join TBL_NAFETHAH_USER_IDENTIFICATION uident
on ( (usr.userId = uident.USER_ID and uident.ID_TYPE = 1) or (usr.userId = uident.USER_ID and uident.ID_TYPE = 2) )
inner join TBL_NAFETHAH_LOOKUP_VALUE nlookup
on nlookup.LOOKUP_KEY = uident.ID_TYPE
and nlookup.CATEGORY_ID = 9
inner join TBL_NAFETHAH_LOOKUP_VALUE nlookup2
on nlookup2.LOOKUP_KEY = ncasestage.CASE_STAGE
and nlookup2.CATEGORY_ID = 15
where nuser.MAKE_PUBLIC = 1
I want to put one more condition in this line
inner join TBL_NAFETHAH_USER_IDENTIFICATION uident on ( (usr.userId = uident.USER_ID and uident.ID_TYPE = 1) or (usr.userId = uident.USER_ID and uident.ID_TYPE = 2) )
If this condition does not met, ie empty (usr.userId = uident.USER_ID and uident.ID_TYPE = 1) or (usr.userId = uident.USER_ID and uident.ID_TYPE = 2)m then I have to add another condition (usr.userId = uident.USER_ID) and if it returns muliple row only take first row.
How to achieve it?

Answer 1

If you want to omit missing records from the TBL_NAFETHAH_USER_IDENTIFICATION table then INNER JOIN a sub query that returns the first record that meets the criteria with a useful ORDER BY.
inner join
(
SELECT TOP(1) * FROM TBL_NAFETHAH_USER_IDENTIFICATION uident
WHERE usr.userId = uident.USER_ID --AND ID_TYPE IN(1, 2)
ORDER BY ID_TYPE
)
uident ON usr.userId = uident.USER_ID
If you want to include records without a match from the TBL_NAFETHAH_USER_IDENTIFICATION table then LEFT OUTER JOIN a sub query that returns the first record that meets the criteria with a useful ORDER BY.
left outer join
(
SELECT TOP(1) * FROM TBL_NAFETHAH_USER_IDENTIFICATION uident
WHERE usr.userId = uident.USER_ID ID_TYPE IN(1, 2)
ORDER BY <SomeValue>
)
uident ON 1=1
NOTE : If there will always be a record in the TBL_NAFETHAH_USER_IDENTIFICATION for each user then you can order by ID_TYPE and take the first row. If 1 and 2 are the first two values in ID_TYPE, this will guarantee that if there is a type of 1 or 2 then it will come first. If you have a type of 0,-1,A, B, etc, then you will have to add a virtual rank column via another sub query.