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Thread: Can i get help with relational Algebra?

  1. #1
    Join Date
    Mar 2013
    Posts
    1

    Can i get help with relational Algebra?

    I want to start learning about SQL, and wants to understand a little Relational Algebra.

    I started with basic exercize, but dont know where to start.

    I got 3 relations:

    Ingredients(ingredients_id, iname, price)
    Recipe(recipe_id, rname, type, portions)
    Contains(recipe_id, ingredients_id, amount)

    And now i want to write the query or draw the query tree that will output the following:

    1. a list with ingredients and amount for Recipe "Meatballs"
    2. a list with all recipenames, for recipes that ONLY contains ingredients that costs less than 40
    3. Recipename for recipes that contains "Eggs" but not "Chilli"

    I hope u could help me, get started

  2. #2
    Join Date
    Nov 2002
    Location
    New Jersey, USA
    Posts
    3,921
    Looks like a homework to me. What have you tried so far?. These are fairly straight forward queries requiring you to join tables or tuples in your case.

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