sql, getting parents and child from one table - sql

Question

I'm trying to write a simple sql statement to select a parent and dependents from one table based on the parents hiring date. Because the hiring date field in dependents row is null, I'm only getting the parents. Can someone help?
PRIM KEY RECORD LAST FIRST HIRE DATE
12345 1 JONES MARY 1/1/2017
12345 2 JONES TIM
6789 1 SMITH CAROL 5/12/2014
23456 1 WHITAKE REGINA 5/14/2017
23456 2 WHITAKE JOE
parent has a row for each child in the table. Parent is 1 and all dependents have a 2. They share a primary key (parent's ssn). I want to select all parents who was hired between specific date range and their dependants rows. The dependent hire date column is null. So when I write the following... I'm only getting the parent rows...
SELECT PRIMARY_KEY_VALUE, RECORD_ID, LAST_NAME, FIRST_NAME, HIRE_DATE
FROM CIGNA_ELIGIBILITY
WHERE(HIRE_DATE BETWEEN '20171101' AND '20171131');

Answer 1

If i understand your problem correctly, that on the date range provided, you want to return records associated with it and all dependents(provided that parents/childs has same prim_key) then one way could be to use IN.
select *
from table1 t1
where t1.prim_key in
(
select t2.prim_key
from table1 t2
where t2.hire_date between '2017-01-01' AND '2017-01-30'
);
what the above query does is that from sub-query select PRIM_KEY of the date range specified and then in main query select all record associated with it.
Result:
+---+----------+--------+-------+-------+---------------------+
| | prim_key | record | last | first | hire_date |
+---+----------+--------+-------+-------+---------------------+
| 1 | 12345 | 1 | JONES | MARY | 01.01.2017 00:00:00 |
| 2 | 12345 | 2 | JONES | TIM | NULL |
+---+----------+--------+-------+-------+---------------------+
DEMO
Update:
Another option could be to use exists:
select *
from table1 t1
where exists
(
select 1
from table1 t2
where t1.prim_key = t2.prim_key
and t2.hire_date between '2017-01-01' AND '2017-01-30'
)