mysql cant' get null data to show up in query - mysql

Question

Here is what I need to achieve:
person_id last_name first_name region_id region name
1 barnum phineas 1 maricopa
2 loman willy 2 pima
2 loman willy 3 pinal
2 loman willy 4 santa cruz
3 kay mary 5 cochise
3 kay mary 6 gila
3 kay mary 7 graham
4 lillian vernon NULL NULL
Here are my tables:
Create database sales
use sales
create table if not exists
`Sales_People`
(`person_id` int primary key,
`last_name` char(16) not null,
`first_name` char(16) not null);
INSERT INTO Sales_people
(`person_id`, `last_name`, `first_name`)
values
('1', 'barnum', 'phineas'),
('2', 'loman', 'willy'),
('3', 'kay', 'mary'),
('4', 'lillian', 'vernon');
create table if not exists
`Sales_Region`
(`region_id` int primary key,
`name` char(16) not null);
INSERT INTO Sales_Region
(`region_id`, `name`)
Values
('1', 'maricopa'),
('2', 'pima'),
('3', 'pinal'),
('4', 'santa cruz'),
('5', 'cochise'),
('6', 'gila'),
('7', 'graham');
create table if not exists
`Sales_People_Region`
(`person_id` int not null,
`region_id` int not null,
constraint spr_pk primary key(person_id, region_id),
constraint spr_fk1 foreign key(person_id)
references Sales_People(person_id),
constraint spr_fk2 foreign key(region_id)
references Sales_Region(region_id));
INSERT INTO Sales_People_Region
(`person_id`, `region_id`)
Values
('1', '1'),
('2', '2'),
('2','3'),
('2', '4'),
('3', '5'),
('3', '6'),
('3','7');
create table if not exists
`Sales`
(`year` int not null,
`month` int not null,
`region_id` int not null,
`amount_sold` decimal(11,2),
constraint s_pk primary key(year, month, region_id),
constraint s_fk foreign key(region_id)
references Sales_Region(region_id));
INSERT INTO Sales
(`year`, `month`, `region_id`, `amount_sold`)
Values
('2016', '01', '1', '800000'),
('2016', '02', '1', '850000'),
('2016', '03', '1', '990000'),
('2016', '01', '2', '425000'),
('2016', '02', '2', '440000'),
('2016', '03', '2', '450000'),
('2016', '01', '3', '200000'),
('2016', '02', '3', '210000'),
('2016', '03', '3', '220000'),
('2016', '01', '4', '50000'),
('2016','02', '4', '52000'),
('2016', '03', '4', '55000'),
('2016', '01', '5', '40000'),
('2016', '02', '5', '41000'),
('2016', '03', '5', '42000'),
('2016', '01', '6', '3000'),
('2016', '02', '6', '31000'),
('2016','03', '6', '32000'),
('2016', '01', '7', '20000'),
('2016', '02', '7', '21000'),
('2016', '03', '7', '22000');
here is my code:
select sales_people.person_id, `last_name`, `first_name`, sales_region.Region_id,
trim(sales_region.`name`) AS 'Region Name'
from `sales_region`
inner join sales_people_region
on sales_people_region.region_id = sales_region.region_id
inner join sales_people
on sales_people_region.`person_id` = sales_people.`person_id`
group by sales_region.region_id, sales_people.person_id
having sales_people.person_id >= ''
order by sales_people.person_id, sales_region.region_id asc;
what I get:
person_id last_name first_name Region_id "Region Name"
1 barnum phineas 1 maricopa
2 loman willy 2 pima
2 loman willy 3 pinal
2 loman willy 4 "santa cruz"
3 kay mary 5 cochise
3 kay mary 6 gila
3 kay mary 7 graham
I can't get it to let me see the last person_id because they have no region_ids assigned to them. In the table sales_people_region region_id is a primary key and therefore not able to be null.
If I query sales_people and group by person_id she does come up.

Answer 1

I think an outer join would remedy this. An inner join requires there to be at least one row extant on each side of the join; a left outer join will select all rows from the left-hand table including those for which there is no matching row in the right-hand table. (A right outer join is the mirror image of this, and a full outer join selects unmatched rows from both sides.)
Try this query:
SELECT sales_people.person_id, last_name, first_name, sales_region.Region_id,
TRIM(sales_region.`name`) AS 'Region Name'
FROM sales_people
LEFT OUTER JOIN sales_people_region
on sales_people.person_id = sales_people_region.person_id
LEFT OUTER JOIN sales_region
ON sales_people_region.region_id = sales_region.region_id
GROUP BY sales_region.region_id, sales_people.person_id
HAVING sales_people.person_id != ''
ORDER BY sales_people.person_id, sales_region.region_id ASC;