SWEN-220 Lecture 2: 09_01_2017 Notes
11 Sep 2017
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Document Summary
Subtract the second dataset from the first dataset. {1,2} x {3,4} = { (1,3), (1,4), (2,3), (2,4) } Removes or keeps a specific subset of the dataset. Selects from a table based on an attribute. Selects from a table and then renames the attributes accordingly combines two tables on a common column. Table that contains the both of two other tables. Checks which rows contains both of the set that you"re dividing by, and the attribute of. Double circle indicates that you can have more than one. Derived attributes is an attribute that isnt given or in the database, but can be computed. If it"s underlined, then it is the key.
