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Union and intersection

Union and intersection

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  • 1. Disclaimer: This presentation is prepared by trainees ofbaabtra as a part of mentoring program. This is not officialdocument of baabtra –Mentoring PartnerBaabtra-Mentoring Partner is the mentoring division of baabte System Technologies Pvt .Ltd
  • 2. Union and Intersection Zabeeb anwar zabeebanwar@gmail.com www.fb.com/zabeebanwar twitter.com/zabeebanwar in/linkedin.com/in/zabeeb 9895599689
  • 3. union AUB- AUB(OR) means the union of sets A and B contains all of the elements of both A and B.
  • 4. IntersectionAÇB(AND) means the intersection of sets Aand B. This contains all of the elements whichare in both A and B.
  • 5. Union and Intersection with empty
  • 6. Union and Intersection in Psql
  • 7. 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.
  • 8. 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);
  • 9. Union• hotstartup=# select * from clients union select * from vips; name ---------------- Sharan Vineesh Bala Sheethal Reshmi Anupa Ashwathy (7 rows)
  • 10. Union All• hotstartup=# select * from clients union all select * from vips; name ---------------- Sharan Vineesh Bala Sheethal Reshmi sheethal Anupa Ashwathy (8 rows)
  • 11. 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)
  • 12. Intersect All• Lets insert a Sheethal(duplicate name) into VIP’s. name ---------------- Sharan Vineesh Bala Sheethal Sheethal (4 rows)-select * from client intersect all select * from vips;
  • 13. 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.
  • 14. 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
  • 15. Except All• Lets insert a Sheethal(duplicate name) into clients. name ---------------- Sharan Vineesh Bala Sheethal Sheethal (4 rows)-select * from clients except all select * from vips;
  • 16. Except All name----------------SharanVineeshBalaSheethal (4 rows)
  • 17. Where Clause• select * from Clients_Year; name | Birth year ------------------+------ Sharan | 1976 Vineesh | 1977 Bala | 1978 Ashwathy | 1983 Reshmi | 199 3 sheethal | 1996 Anupa | 1997
  • 18. 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
  • 19. 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
  • 20. Union and intersection in Python
  • 21. Example>>>engineers = Set([John, Jane, Jack, Janice])>>>programmers = Set([Jack, Sam, Susan, Janice])>>>managers = Set([Jane, Jack, Susan, Zack])
  • 22. Union>>>employees = engineers | programmers | managers>>>print “employees”Set([Jane, Janice, John’, Jack’,’susan’,’Zack’,’sam’])
  • 23. Intersection>>>engineers = Set([John, Jane, Jack, Janice])>>>managers = Set([Jane, Jack, Susan, Zack])>>>engineering_management = engineers & managers>>>print “engineering_management”Set([Jane, Jack’])
  • 24. Questions
  • 25. 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
  • 26. Contact Us