SQL getting multiple rows in PARTICULAR sql - sql

Question

I have a table abc with following rows:
emp_id_role Group_name Role_name Location_id
12 Insurance Manager Noida
12 Insurance Senior Manager Noida
13 Global Client Services Sw UP
14 Operations Management All Jobs kERALA
and another master table with all the details employee_xyz:
PERSON_ID NAME DOB START_DATE END_DATE SSN
12 DEAN 01-JAN-1990 01-JAN-2017 20-JAN-2017 847474
12 DEAN 01-JAN-1990 21-JAN-2017 03-mar-2018 847474
12 DEAN 01-JAN-1990 04-mar2018 31-DEC-4712 847474
13 SAM 20-JAN-1990 17-JAN-2016 20-JAN-2017 847474
13 SAM 20-JAN-1990 21-JAN-2017 31-DEC-4712 847474
14 JAY 29-dec-1990 21-JAN-2016 31-DEC-4712 847474
I want to fetch the full names from the table employee_xyz for the records in table abc.
When I'm joining these two using the below queries I'm getting more number of rows for an employee than in table abc,
Eg: for employee_id 12 I should get 2 rows as in table abc but I'm getting 9 rows somehow...
Query used is simple :
select * from table_abc abc,
employee_xyz xyz
where xyz.person_id=abc.emp_id_role
and trunc(sysdate) between abc.Start_date and xyz.end_date
and person_id=12;

Answer 1

I suppose you want to select all columns from table_abc with names from employee_xyz.
If your try with select abc.*, xyz.name, you already able to select as two rows since sysdate for person_id= 12 stays in the interval only for third row(start_date:04-mar2018/ end_date:31-DEC-4712) but if you want non-repeating even with more date values stay, you can use distinct : select distinct abc.*, xyz.name as below( where there're two rows in the interval second row's end date converted from '2018-03-03' to '2019-03-03' ) :
with table_abc(emp_id_role, Group_name, Role_name, Location_id) as
(
select 12,'Insurance','Manager','Noida' from dual union all
select 12,'Insurance','Senior Manager','Noida' from dual union all
select 13,'Global Client Services','Sw', 'UP' from dual union all
select 14,'Operations Management','All Jobs','kERALA' from dual
),
employee_xyz(person_id,name, dob, start_date, end_date, ssn) as
(
select 12,'DEAN',date'1990-01-01',date'2017-01-01',date'2017-01-20',847474 from dual union all
select 12,'DEAN',date'1990-01-01',date'2017-01-21',date'2019-03-03',847474 from dual union all
select 12,'DEAN',date'1990-01-01',date'2018-03-04',date'4712-12-31',847474 from dual
)
select distinct abc.*, xyz.name
from table_abc abc join employee_xyz xyz
on xyz.person_id = abc.emp_id_role
where trunc(sysdate) between xyz.Start_date and xyz.end_date
and person_id = 12;
EMP_ID_ROLE GROUP_NAME ROLE_NAME LOCATION_ID NAME
----------- ---------- --------------- ----------- -----
12 Insurance Manager Noida DEAN
12 Insurance Senior Manager Noida DEAN