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maxonik [38]
3 years ago
9

Consider the relational schema below: Students(sid: integer, sname: string, major: string) Courses(cid: integer, cname: string,

hours: integer) Enrollment(sid: integer, cid: integer, grade: real) Write a relational algebra expression that satisfies this query? Find the distinct names of all students that take at least three courses and major in "Philosophy".
Computers and Technology
1 answer:
daser333 [38]3 years ago
7 0

Solution :

Here, we need to perform JOIN operation of the students and registration.

Use NATURAL JOIN operator \Join and so no need to specify Join condition.

Also we need to selection operator tp select only those course whose major in "philosophy".

Finally we projection operator π to project only distinct students name who took at least three courses.

$\pi [\sigma_{\text{student's nam}e} [ \sigma(\text{three courses}) \Join \text{"Philosophy"}]]$

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Read 2 more answers
What do u do to me pepa
Maru [420]
Peppa: Hello Susie!

Susie: *mehhh* Hello Peppa!
What are you doing?
Peppa: I'm learning to whistle,

but I can't do it yet.
Susie: Hmm.. that sounds hard.
Peppa: It's impossible!
Uh.. can you whistle Susie?
Susie: No

Peppa: *honk* Oh good! I mean-
that's sad if you can't whistle

but good because I can't whistle

Susie: What's whistling anyway?
Peppa: You put your lips together
and blow!
Susie: Like this? *whistles*
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