SQL Join commands to discover highest level of product - mysql

Question

So basically what I am trying to do is this... My task is to find people who have "CSM", "LSP" or "CSD" but also joining information from Table "client_personal" that matches the "client_no" from the results of the search on "CSM", "LSP", or "CSD"
Im sure Im doing this all "bass ackwords" but end goal is to show customer information including other fields in table "client_personal" so sales can do a sales pitch for those who have "CSM" but not records of "LSP" or "CSD" (considered higher levels) - Unfortunately there is 1: an assload of mess, tons of dupes, and multiple entries and 2: theres not an easier database to work with that would have "highest level achieved".
SELECT client_no,product,status,paid_date
FROM client_educational
LEFT JOIN client_personal
ON client_educational.client_no = client_personal.client_no
WHERE product='CSM'
OR product='LSP'
OR product='CSD'
Heres the databases that I am interested in:
client_educational
client_no product status pd_date
500000 CSM pd-cert 2018-06-20
500001 CSM pd-cert 2018-06-20
500001 LSP pd-cert 2018-06-20
500002 CSM pd-cert 2018-06-20
500002 LSP pd-cert 2018-06-20
500002 CSD pd-cert 2018-06-20
client_personal
client_no name email phone
500000 John Doe mail#mail.com 555-555-5555
500001 John Shmoe mail#mail.com 555-555-5555
500002 John Howe mail#mail.com 555-555-5555
So what Im needing is not only to combine the results, but also display only those who only have product "CSM" but not "LSP" or "CSD" by using the "client_no" row as the unique identifier....
Something like this...
client_no product status pd_date name email phone
500000 CSM pd-cert 2018-06-20 John Doe mail#mail.com 555-555-5555

Answer 1

Try it use left join
select
T1.`client_no`,
T2.`product`,
T2.`status`,
T2.`pd_date`,
T1.`name`,
T1.`email`,
T1.`phone`
from client_personal T1
left join client_educational T2 on T1.`client_no` = T2.`client_no`
and T2.`product` = 'CSM'
left join client_educational T3 on T1.`client_no` = T3.`client_no`
and T3.`product` IN('LSP', 'CSD')
where T2.`client_no` is not null
and T3.`client_no` is null
| client_no | product | status | pd_date | name | email | phone |
| 500000 | CSM | pd-cert | 2018-06-20 00:00:00 | John Doe | mail#mail.com | 555-555-5555 |
TEST DDL
CREATE TABLE client_educational
(`client_no` int, `product` varchar(3), `status` varchar(7), `pd_date` datetime)
;
INSERT INTO client_educational
(`client_no`, `product`, `status`, `pd_date`)
VALUES
(500000, 'CSM', 'pd-cert', '2018-06-20 00:00:00'),
(500001, 'CSM', 'pd-cert', '2018-06-20 00:00:00'),
(500001, 'LSP', 'pd-cert', '2018-06-20 00:00:00'),
(500002, 'CSM', 'pd-cert', '2018-06-20 00:00:00'),
(500002, 'LSP', 'pd-cert', '2018-06-20 00:00:00'),
(500002, 'CSD', 'pd-cert', '2018-06-20 00:00:00')
;
CREATE TABLE client_personal
(`client_no` int, `name` varchar(10), `email` varchar(13), `phone` varchar(12))
;
INSERT INTO client_personal
(`client_no`, `name`, `email`, `phone`)
VALUES
(500000, 'John Doe', 'mail#mail.com', '555-555-5555'),
(500001, 'John Shmoe', 'mail#mail.com', '555-555-5555'),
(500002, 'John Howe', 'mail#mail.com', '555-555-5555')
;
DB Fiddle - TEST DEMO

Answer 2

You could use conditional aggregation checks for your criteria display only those who only have product "CSM" but not "LSP" or "CSD"
select cp.client_no,cp.name,cp.email,cp.phone
from client_personal cp
join client_educational ce on cp.client_no = ce.client_no
group by cp.client_no,cp.name,cp.email,cp.phone
having sum(ce.product = 'CSM') > 0
and sum(ce.product IN('LSP', 'CSD')) = 0
In mysql when an expression is used inside sum(a= b) it will result as a boolean 0/1 so you can get your conditional count using above.
Another way using exists
select cp.*
from client_personal cp
join client_educational ce on cp.client_no = ce.client_no
where ce.product = 'CSM'
and not exists (
select 1
from client_educational
where product IN('LSP', 'CSD')
and client_no = cp.client_no
)
Demo for both queries