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Union and intersection


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Union and intersection

  1. 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. 2. Union and IntersectionZabeeb
  3. 3. unionAUB- AUB(OR) means the union of sets A and Bcontains all of the elements of both A and B.
  4. 4. IntersectionAÇB(AND) means the intersection of sets Aand B. This contains all of the elements whichare in both A and B.
  5. 5. Union and Intersection with empty
  6. 6. Union and Intersection in Psql
  7. 7. Union- A hot startup is holding a special event andwants to send out invites for my marriage()to some of my best clients and also to someVIPs.- Some of the VIPs are actually very supportiveof the site and are clients too.- What query will provide the complete set ofpeople to invite avoiding duplicate records?- Here is our data.
  8. 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. 9. Union• hotstartup=# select * from clients union select *from vips;name----------------SharanVineeshBalaSheethalReshmiAnupaAshwathy(7 rows)
  10. 10. Union All• hotstartup=# select * from clients union all select * from vips;name----------------SharanVineeshBalaSheethalReshmisheethalAnupaAshwathy(8 rows)
  11. 11. Intersect• if I want to get the list of people who are bothclients and VIP we can use INTERSECT.• hotstartup=# select * fromclients intersect select * from vips;name----------------Sheethal(1 row)
  12. 12. Intersect All• Lets insert a Sheethal(duplicate name) into VIP’ rows)-select * from client intersect all select * from vips;
  13. 13. Intersect Allname----------------sheethalsheethal(2 rows)- Sheethal appears in both tables twice so wefind two matching pairs for her and hence tworows appears in the results.
  14. 14. Except• I want everyone on the clients list EXCEPT those onthe VIP list.• select * from clients except select * from vips;name----------------SharanVineeshBala
  15. 15. Except All• Lets insert a Sheethal(duplicate name) into rows)-select * from clients except all select * from vips;
  16. 16. Except Allname----------------SharanVineeshBalaSheethal(4 rows)
  17. 17. Where Clause• select * from Clients_Year;name | Birth year------------------+------Sharan | 1976Vineesh | 1977Bala | 1978Ashwathy | 1983Reshmi | 199 3sheethal | 1996Anupa | 1997
  18. 18. Where Clause• select * from clients_year where yearbetween 1970 and 1979 union select * fromceos where year=1977;name | Birth year------------------+------Sharan | 1976Vineesh | 1977Bala | 1978
  19. 19. Do not• select * from clients where year between1970 and 1979 union select name from clientswhere year=1977;ERROR: each UNION query must have thesame number of columns
  20. 20. Union and intersection in Python
  21. 21. Example>>>engineers = Set([John, Jane, Jack,Janice])>>>programmers = Set([Jack, Sam, Susan,Janice])>>>managers = Set([Jane, Jack, Susan,Zack])
  22. 22. Union>>>employees = engineers | programmers |managers>>>print “employees”Set([Jane, Janice, John’,Jack’,’susan’,’Zack’,’sam’])
  23. 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. 24. Questions
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