Getting stuck doing a complicated SQL query for patent research purposes - mysql

Question

I am trying to gather data for a research study for my university thesis. Unfortunately I am not a computer science or programming expert and do not have any SQL experience.
For my thesis I need to do a SQL query answering the question: "Give me all patents of a company X where there is more than one applicant (other company) in a specific time span". The data I want to extract is stored on a database called PATSTAT (where I have a 1 month trial) and is using - dont be surprised SQL.
I tried a lot of queries but all the time I am getting different syntax errors.
This is how the interface looks like:
http://www10.pic-upload.de/07.07.13/7u5bqf7jsow.png
I think I have a really good understanding of what (also from an SQL POV) needs to be done but I cannot execute it.
My idea: As result I want the names of the companies (with reference to the company entered below)
SELECT person_name from tls206_person table
Now because I need a criteria like
WHERE nb_applicants > 1 from tls201_appln table
I need to join these two tables tls206 and tls201. I did read some brief introduction guide on SQL (provided by european patent office) and because both tables have no common "reference key" we need to use the table tls207_pers_appln als "intermediate" so to speak. Now thats the point where I am getting stuck. I tried the following but this is not working
SELECT person_name, tls201_appln.nb_applicants
FROM tls206_person
INNER JOIN tls207_pers_appln ON tls206_person.person_id= tls207_pers_appln.person_id
INNER JOIN tls207_pers_appln ON tls201_appln.appln_id=tls201_appln.appln_id
WHERE person_name = "%Samsung%"
AND tls201_appln.nb_applicants > 1
AND tls201_appln.ipr_type = "PI"
I get the following error: "0:37:11 [SELECT - 0 row(s), 0 secs] [Error Code: 1064, SQL State: 0] Not unique table/alias: 'tls207_pers_appln'"
I think for just 4 Hours SQL my approach is not to bad but I really need some guidance on how to proceed because I am not making any progress.
Ideally I would like to count (for every company) and for every row respectively how many "nb_applicants" were found.
If you need further information for giving me guidance, just let me know.
Looking forward to your answers.
Best regards
Kendels

Answer 1

another way of doing the same thing, which you might find easier to understand (if you are new to sql it is impressive you have got so far), is:
SELECT tls206_person.person_name, tls201_appln.nb_applicants
FROM tls206_person, tls207_pers_appln, tls201_appln
WHERE tls206_person.person_id = tls207_pers_appln.person_id
AND tls201_appln.appln_id = tls201_appln.appln_id
AND tls206_person.person_name LIKE "%Samsung%"
AND tls201_appln.nb_applicants > 1
AND tls201_appln.ipr_type = "PI"
(it's equivalent to the other answer, but instead of trying to understand the JOIN syntax, you just write out all the logic and SQL is smart enough to make it work - this is often called the "new" or "ISO" inner join syntax, if you want to google for more info) (although it is possible, i suppose, that this newer syntax isn't supported by the database you are using).

Answer 2

You are referencing the table tls201_appln, but it is not in the from clause. I am guessing that the second reference to tls207_pers_appln should be to the other table:
SELECT person_name, tls201_appln.nb_applicants
FROM tls206_person
INNER JOIN tls207_pers_appln ON tls206_person.person_id = tls207_pers_appln.person_id
INNER JOIN tls201_appln ON tls201_appln.appln_id = tls207_pers_appln.appln_id
WHERE person_name like '%Samsung%"'
AND tls201_appln.nb_applicants > 1
AND tls201_appln.ipr_type = "PI"

Answer 3

For my thesis I need to do a SQL query answering the question: "Give me all patents of a company X where there is more than one applicant (other company) in a specific time span".
Let me rephrase that for you :
SELECT * FROM patents p -- : "Give me all patents
WHERE p.company = 'X' -- of a company X
AND EXISTS ( -- where there is
SELECT *
FROM applicants x1
WHERE x1.patent_id = p.patent_id
AND x1.company <> 'X' -- another company:: exclude ourselves
AND x1.application_date >= $begin_date -- in a specific time span
AND x1.application_date < $end_date
-- more than one applicant (other company)
-- To avoid aggregation: Just repeat the same subquery
AND EXISTS ( -- where there is
SELECT *
FROM applicants x2
WHERE x2.patent_id = p.patent_id
AND x2.company <> 'X' -- another company:: exclude ourselves
AND x2.company <> x1.company -- :: exclude other other company, too
AND x2.application_date >= $begin_date -- in a specific time span
AND x2.application_date < $end_date
)
)
;
[Note: Since the OP did not give any table definitions, I had to invent these]
This is not the perfect query, but it does express your intentions. Given sane keys/indexes it will perform reasonably, too.