This document discusses union and intersection operations in PostgreSQL and Python. It provides examples of using UNION, INTERSECT, EXCEPT to combine result sets from multiple tables and avoid duplicates. It also shows how to perform union and intersection on sets in Python by using the pipe (|) and ampersand (&) operators. The document is intended as a training presentation for mentoring programs at Baabtra, a mentoring company.

2. Disclaimer: This presentation is prepared by trainees of
baabtra as a part of mentoring program. This is not official
document of baabtra –Mentoring Partner
Baabtra-Mentoring Partner is the mentoring division of baabte System Technologies Pvt .
Ltd

3. Union and Intersection
Zabeeb anwar
zabeebanwar@gmail.com
www.fb.com/zabeebanwar
twitter.com/zabeebanwar
in/linkedin.com/in/zabeeb
9895599689

4. union
AUB
- AUB(OR) means the union of sets A and B
contains all of the elements of both A and B.

5. Intersection
AÇB(AND) means the intersection of sets A
and B. This contains all of the elements which
are in both A and B.

6. Union and Intersection with empty

7. Union and Intersection in Psql

8. Union
- A hot startup is holding a special event and
wants to send out invites for my marriage()
to some of my best clients and also to some
VIPs.
- Some of the VIPs are actually very supportive
of the site and are clients too.
- What query will provide the complete set of
people to invite avoiding duplicate records?
- Here is our data.

9. Union
• create database hotstartup;
• create table clients(name varchar);
insert into clients values(‘Sharan');
insert into clients values(‘Vineesh');
insert into clients values(‘Bala');
insert into clients values(‘Sheethal');
• create table vips(name varchar);
insert into vips values(‘Reshmi');
insert into vips values(‘Sheethal');
insert into vips values(‘Anupa');
insert into vips values(‘Ashwathy');

10. Union
• hotstartup=# select * from clients union select *
from vips;
name
----------------
Sharan
Vineesh
Bala
Sheethal
Reshmi
Anupa
Ashwathy
(7 rows)

11. Union All
• hotstartup=# select * from clients union all select * from vips;
name
----------------
Sharan
Vineesh
Bala
Sheethal
Reshmi
sheethal
Anupa
Ashwathy
(8 rows)

12. Intersect
• if I want to get the list of people who are both
clients and VIP we can use INTERSECT.
• hotstartup=# select * from
clients intersect select * from vips;
name
----------------
Sheethal
(1 row)

13. Intersect All
• Let's insert a Sheethal(duplicate name) into VIP’s.
name
----------------
Sharan
Vineesh
Bala
Sheethal
Sheethal
(4 rows)
-select * from client intersect all select * from vips;

14. Intersect All
name
----------------
sheethal
sheethal
(2 rows)
- Sheethal appears in both tables twice so we
find two matching pairs for her and hence two
rows appears in the results.

15. Except
• I want everyone on the clients list EXCEPT those on
the VIP list.
• select * from clients except select * from vips;
name
----------------
Sharan
Vineesh
Bala

16. Except All
• Let's insert a Sheethal(duplicate name) into clients.
name
----------------
Sharan
Vineesh
Bala
Sheethal
Sheethal
(4 rows)
-select * from clients except all select * from vips;

17. Except All
name
----------------
Sharan
Vineesh
Bala
Sheethal
(4 rows)

18. Where Clause
• select * from Clients_Year;
name | Birth year
------------------+------
Sharan | 1976
Vineesh | 1977
Bala | 1978
Ashwathy | 1983
Reshmi | 199 3
sheethal | 1996
Anupa | 1997

19. Where Clause
• select * from clients_year where year
between 1970 and 1979 union select * from
ceos where year=1977;
name | Birth year
------------------+------
Sharan | 1976
Vineesh | 1977
Bala | 1978

20. Do not
• select * from clients where year between
1970 and 1979 union select name from clients
where year=1977;
ERROR: each UNION query must have the
same number of columns

21. Union and intersection in Python

22. Example
>>>engineers = Set(['John', 'Jane', 'Jack',
'Janice'])
>>>programmers = Set(['Jack', 'Sam', 'Susan',
'Janice'])
>>>managers = Set(['Jane', 'Jack', 'Susan',
'Zack'])

23. Union
>>>employees = engineers | programmers |
managers
>>>print “employees”
Set(['Jane', 'Janice', 'John’,
'Jack’,’susan’,’Zack’,’sam’])

24. Intersection
>>>engineers = Set(['John', 'Jane', 'Jack',
'Janice'])
>>>managers = Set(['Jane', 'Jack', 'Susan',
'Zack'])
>>>engineering_management = engineers &
managers
>>>print “engineering_management”
Set(['Jane', 'Jack’])

25. Questions

27. If this presentation helped you, please visit our
page facebook.com/baabtra and like it.
Thanks in advance.
www.baabtra.com | www.massbaab.com |www.baabte.com

28. Contact Us