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DBMS Korth Edition 6 Exercise 2 Question 6 (Page No. 54)

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Consider the following expressions, which use the result of a relational
algebra operation as the input to another operation. For each expression,
explain in words what the expression does.

  1.  $\sigma _{year\geq 2009}(takes)\Join student$
  2.  $\sigma _{year\geq 2009}(takes \Join student)$
  3. $\pi _{ID,name,course_id}(student \times takes)$
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ajaysoni1924 asked Mar 23, 2019
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DBMS Korth Edition 6 Exercise 2 Question 10 (Page No. 54)
Consider the advisor relation shown in Figure , with s id as the primary key of advisor. Suppose a student can have more than one advisor. Then, would s id still be a primary key of the advisor relation? If not, what should the primary key of advisor be?
Consider the advisor relation shown in Figure , with s id as the primarykey of advisor. Suppose a student can have more than one advisor. Then,would s id still be a prima...
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