html5-img
1 / 5

Relational Algebra and SQL

Relational Algebra and SQL. Given relational schema: Frequent ( D, P ) Serves ( P, B ) Likes ( D, B ) Attributes: P (pub), B (beer), D (drinker) The pubs that serve a beer that Jefferson likes. Drinkers that frequent at least one pub that serves “Bud” or “Becks”.

bmays
Télécharger la présentation

Relational Algebra and SQL

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Relational Algebra and SQL Given relational schema: Frequent (D, P) Serves (P, B) Likes (D, B) Attributes: P (pub), B (beer), D (drinker) • The pubs that serve a beer that Jefferson likes. • Drinkers that frequent at least one pub that serves “Bud” or “Becks”. • Drinkers that frequent only pubs that serve some beer they like • Drinkers that frequent only pubs that serve no beer they like.

  2. 1) Algebra • Solution 1: • Solution 2: • Solution 3: • Solution 4:

  3. 2) SQL SELECT p FROM S, L WHERE S.b=L.b AND L.d=‘Jefferson’ • Solution 1: • Solution 2: SELECT d FROM F WHERE F.p in (SELECT p FROM S WHERE b IN (‘Bud”, ‘Becks’))

  4. 2) SQL SELECT d FROM F EXCEPT SELECT d FROM (SELECT* FROM F EXCEPT SELECT d,p FROM S, L WHERE S.b = L.b) • Solution 3:

  5. 2) SQL SELECT d FROM F EXCEPT SELECT d FROM (SELECT * FROM F INTERSECT SELECT d,p FROM S, L WHERE S.b = L.b) • Solution 4: • Solution 4 (alternative solution): SELECT d FROM F WHERE (SELECT COUNT (DISTINCT p) FROM S, L WHERE F.p=S.p AND S.b=L.b AND L.d=F.d) = 0

More Related