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Consider the below schema for a library database and write relational algebra expressions for the following queries
1. Author ( authorname, citizenship, birthyear)
2. Book (isbn, title, authorname)
3. Topic (isbn, subject)
4. Branch (libname, city)
5. Instock (isbn, libname, quantity)
1. Give all authors’ names born after 1940. [0.25 Point]
2. Give the names of libraries in Sydney. [0.25 Point]
3. Give the city/cities and “isbn” where each book is held. [0.25 Point]
4. Give the title of each book on the topic of either alcohol or drugs. [0.25 Point]
5. Give the title and author of each book of which at least two copies are held in a branch located in Melbourne. [0.50 Point]
What is the different between the database schema and the database instance? Give an example for each.
Name at least three tables that might be used to store information in the following systems:
a. An e-commerce system such as Amazon. [0.25 Point]
b. A social media system such as Twitter. [0.25 Point]
c. A health care system. [0.25 Point]
d. A university system. [0.25 Point]
Given the relation below named Contact_Info, answer the following questions:
a. What is the relational schema of the relation Contact_Info? [0.25 Point]
b. What is the degree of the giving relation? [0.25 Point]
c. Is the column Name an atomic attribute/value? If no, justify your answer? [0.25 Point]
d. What are the outputs of the given operations?
1. (Contact_Info) [0.50 Point]
2. (Contact_Info) [0.25 Point]
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