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  1. Practice
  2. Databases
  3. Relational Algebra
  4. Basics of Sets and Relations #5
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Basics of Sets and Relations #5

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  • tibi01993 + 0 comments

    http://www.mathsisfun.com/algebra/sigma-notation.html This link explains clearly what is that symbol. FYI

  • aashray18521 + 0 comments

    Mysql equivalent:

        Select count(*)
    from student
    where number<3000;

  • shoeb5436 + 0 comments

    It must return 2. so the answer is 2

  • jacobdickey_2016 + 3 comments

    I dont understand what this is asking

    • manuelj + 0 comments

      This might help:

      σ condition(relation): condition is a boolean expression in which rows are selected for which the condition is true

      Source: http://jcsites.juniata.edu/faculty/rhodes/dbms/relalg.htm

    • brandon_loza15 + 1 comment

      rows are going vertically since they are asking for the number >3000 and the student name it should give you 2 rows

      • manuelj + 0 comments

        The condition is number < 3000, just in case someone gets confused.

    • LSRahul + 0 comments

      What is the count of rows returned in the following relational selection? ans =2

  • raunakpandey1007 + 0 comments

    WRITE 2 AND CLICK ON SUBMIT

  • coder_aky + 0 comments

    :-)

    2

  • grinyahoo_f + 0 comments

    Font size is too little in the expression

  • niteshyadavand21 + 0 comments

    It is just asking how many relation does each person have answer is 2 because 1. Number 2. sex

  • puneeth579 + 0 comments

    Where can I learn about all Notations mentioned in the question? Like Pie Sigma ( sorry I can't find those symbols in keyboard)

  • bwhiting + 1 comment

    I don't understand the notation. Where can I learn this?

    • mohdaasif6Asked to answer + 1 comment

      visit W3schools or TutorialsPoint via Google

      • bwhiting + 2 comments

        what do I search for? I don't know what this notation is called.

        • lmuranga + 0 comments

          σ(Number<3000)(Student) I think you should be thinking about logic , es simple amigo!

        • defrain_3 + 1 comment

          relational algebra

          • bwhiting + 0 comments

            thx

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