COIS 3400H Lecture 9: WEEK 9 LEC NOTES

• School: Trent University
• Department: Computing & Information Systems
• Course: COIS 3400H
• Professor: Zeinab Noorian

Document Summary

Project: represented with pie, vertical projection of selected attributes in the table. Select: represented by sigma, used to select a subset of tuples from a relation based on a condition over relations attributes, horizontal filtering. Rename: rho, is used to rename a relation or its attributes or both. Binary operations: operations that are applied onto more then one table. Union: union is used to include tuples exist in either relations. Union compatible: for two relations to be union compatible, each relation must have, the same number of attributes , the attributes in corresponding columns must have same data types. Intersection is used to include tuples exist in both relations: the relations being used in this set must be union compatible or else the operation cannot be used on the relations. Set difference: minus is used to exclude tuples from a relation.