关于INNER JOIN的Where子句

Question

I have four tables. I need to get data from all of them. Table 'Tenancy_histories' contains the move_in_date, move_out_date, rent columns. 'Profiles' contains the first_name, last_name, email, profile_id etc. 'Referrals' contains the the referrer_bonus_amount and similar other data.

Most importantly it contains the number of referrals made by a particular profile_id which is the number of occurrence of that profile_id in the 'referrer_id(same as profile id)' column. 'Houses' contains the house details occupied by the tenants. Table 'Houses' and 'Profiles' are not directly linked but linked through table 'Tenancy_histories'

I need to write a query to get Fullname, Contact, City and House Details of the tenants who have not referred even once.

I tried something like this but is not getting the desired ouput though not getting any error

SELECT
    pr.first_name + ' ' + pr.last_name AS full_name, pr.phone, 
    pr.[city(hometown)], hs.bhk_details 
FROM
    Profiles pr  
INNER JOIN 
    Tenancy_histories th ON pr.profile_id = th.profile_id 
INNER JOIN 
    Houses hs ON th.house_id = hs.house_id 
INNER JOIN 
    Referrals rf ON pr.profile_id = rf.[referrer_id(same as profile id)] 
WHERE 
    pr.profile_id NOT IN (SELECT [referrer_id(same as profile id)] 
                          FROM Referrals)

Answer 1

Try this:

select full_name , phone,[city(hometown)], bhk_details ,profile_id 
from (
select p.full_name , p.phone,p.[city(hometown)], p.bhk_details ,p.profile_id
from (
select pr.first_name+' '+pr.last_name as full_name, pr.phone, pr.[city(hometown)], hs.bhk_details ,pr.profile_id
from Profiles pr 
INNER JOIN 
Tenancy_histories th 
on pr.profile_id = th.profile_id 
INNER JOIN 
Houses hs 
on th.house_id = hs.house_id 
) as p
left join
Referrals rf 
on p.profile_id = rf.[referrer_id(same as profile id)] 
where rf.[referrer_id(same as profile id)] is null
) as p_r

Answer 2

Simply removing the INNER JOIN to referrals table should do the trick

SELECT
    pr.first_name + ' ' + pr.last_name AS full_name, 
    pr.phone, 
    pr.[city(hometown)], 
    hs.bhk_details 
FROM
    Profiles pr  
INNER JOIN 
    Tenancy_histories th ON pr.profile_id = th.profile_id 
INNER JOIN 
    Houses hs ON th.house_id = hs.house_id 
WHERE 
    pr.profile_id NOT IN (SELECT [referrer_id(same as profile id)] 
                          FROM Referrals)

Answer 3

NOT IN with a subquery is dangerous. If any row in the subquery returns a NULL value then no rows are ever returned.

In addition to removing the inner join to referrals , I would recommend changing the comparison to using NOT EXISTS :

WHERE NOT EXISTS (SELECT 1
                  FROM referrals
                  WHERE pr.profile_id = r.[referrer_id(same as profile id)] 
                 );

The alternative is to use a LEFT JOIN to referrals and simply check that no match is made:

SELECT pr.first_name + ' ' + pr.last_name AS full_name, pr.phone, 
       pr.[city(hometown)], hs.bhk_details 
FROM Profiles pr INNER JOIN 
     Tenancy_histories th
     ON pr.profile_id = th.profile_id INNER JOIN 
     Houses hs
     ON th.house_id = hs.house_id LEFT JOIN 
     Referrals rf
     ON pr.profile_id = rf.[referrer_id(same as profile id)] 
WHERE rf.[referrer_id(same as profile id)] IS NULL;