ECE356 Lecture Notes - Lecture 3: Relational Algebra, Database Server, Boolean Algebra

• School: University of Waterloo
• Department: Electrical and Computer Engineering
• Course: ECE356
• Professor: Zarnett

Document Summary

Lecture 3 relational query languages and sql. A query language is a language in which the user requests information from the database. The operations we want to discuss can be applied to a single relation, or a pair of relations; the result of is always a single relation [sks11]. This means that the output of one operation can be used as the input to another operation, allowing us to chain operations as needed. If it helps you to imagine this, every operation is a function with return type relation and they take either one or two relations as parameters. You will also need to keep in mind that because they all have input and output of relation(s), the operations operate on a set of data, not just a single element. In a c-like language you might write a for loop that sets all elements in an array to be -1.