I need to double check my answer to insure I did it right. Thanky you. Question: Gamer: (UserID, Name, Age, Address, City, Favorite-Game, Rank) Game: (GameID, Name, Company, Release-Year, Version) Store: (StoreID, Name, Address, City) WhereToFind: (GameID, StoreID, Price) Category: (GameID, Category-Name) From the relational schemas illustrated above, use the different relational algebra operators and operations (ρ, σ, π, ⋂, ⋃, -, ⨝) discussed in class to build the following queries: 1. List -by name and ID- each gamer who lives in the city of Chicago, with a rank of 5, and is aged between 15 (included) and 30 (included). 2. List games -by name and release year- that are not in the “Action” category. 3. Since each game can fall within several categories, list games -by name and release year- that are in the “Action” category and also in the “Role-Playing” category
I need to double check my answer to insure I did it right. Thanky you.
Question:
Gamer: (UserID, Name, Age, Address, City, Favorite-Game, Rank)
Game: (GameID, Name, Company, Release-Year, Version)
Store: (StoreID, Name, Address, City)
WhereToFind: (GameID, StoreID, Price)
Category: (GameID, Category-Name)
From the relational schemas illustrated above, use the different relational algebra operators and operations (ρ, σ, π, ⋂, ⋃, -, ⨝) discussed in class to build the following queries:
1. List -by name and ID- each gamer who lives in the city of Chicago, with a rank of 5, and is aged between 15 (included) and 30 (included).
2. List games -by name and release year- that are not in the “Action” category.
3. Since each game can fall within several categories, list games -by name and release year- that are in the “Action” category and also in the “Role-Playing” category
My answers:
1) π UserID, Name ( σ City = ‘Chicago’ ∧ Rank = 5 ∧ Age < 15 ∧ > 30 ( Gamer ))
2) π Name, Release-Year (Game) ⨝Game, GameID = Category, GameID ∧ Category-Name <> “Action” ( Category )
3) π Name, Release-Year (Game) ⨝Game, GameID = Category, GameID ∧ Category-Name = “Action” ∧ Category-Name = “Role-Playing” ( Category )
- In it columns to be displayed are written.
- In it condition are written
is used for and
⨝ is used for join
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