ITM 500 Lecture Notes - Lecture 4: Foreign Key, Unique Key, Data Management

• School: Ryerson University
• Department: Information Technology Management
• Course: ITM 500
• Professor: Raymond Moss

Document Summary

In module 3 you learnt about aggregate queries. Each query generated only 1 row of output regardless of the number of rows selected for the calculation. In this module we will learn how to generate potential multiple rows of aggregate output based on the value of a categorizing attribute. For example instead of producing a single count of the female students we can generate a different count of female students for each major based on the value of the attribute stdmajor. Finally we will look at the basic commands in sql for maintaining data in the database by adding new rows, modifying existing rows and deleting rows. To follow the examples and the your turn" exercises it is recommended to have sql. Server"s management studio opened and the university database attached. List the average gpa for students by major (i. e. for each major) In module 4 we saw the result of aggregate queries.