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14 Cards in this Set
- Front
- Back
- 3rd side (hint)
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What relational model use? Why? |
Tables Represent collection of related data values |
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What do you call the number of attributes? |
Degree or arity |
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Why is a domain a set of atomic values? |
Each value is indivisible as far as the relational model is concerned |
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Does tuples have a particular order? |
False |
True or False |
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Each entity in an entity type need to be identified uniquely |
Each entity in an entity type need to be identified uniquely |
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Give an example one or more attributes that can be used as an entity identifier? |
In grade we have (student#, course#) |
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What is a super key? |
Key attributes + other attributes of relation |
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Give an example of a super key in BANK |
CustomerName, SIN |
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Relations are Values |
Relations are Values |
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Relvars are variables |
Relvars are variables |
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Create a code that find the name and age of all employee who earn more than $50000 per year Create a code that update their salary to $55000 |
SELECT Name, Age FROM Employees WHERE Salary > 50000; UPDATE Employees SET Salary = 55000 WHERE EmployeeID = 1; |
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What do we use to determine how to implement user request |
Optimization |
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How would you optimize a Banking system to search for an account numbers |
Creat an INDEX ind_Account_Number on Account (Account_number) SELECT * FROM Accounts WHERE Account _Number = '123456789'; |
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What is Catalog? |
Collection of metadata that describes the database object (tables, views, functions) |
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