INFO 328 HW 2

INFO 328 HW 2 - Homework Assignment #2 (2.13, 2.14, 2.18,...

Info iconThis preview shows page 1. Sign up to view the full content.

View Full Document Right Arrow Icon
Homework Assignment #2 (2.13, 2.14, 2.18, 2.32, 2.33, 2.34) 2.13 A primary key is a candidate key chosen to be the main key for the relation, every table should have a primary key. A candidate key is called a candidate because it is a candidate to become the primary key. A candidate key is a unique key. 2.14 A primary key is always unique; it doesn’t allow a null or empty space. A primary key allows you to uniquely identify a single row. A primary key allows you to find one single record based on a category. A primary key allows you to sort out categories and identify them uniquely. Examples would include an employee id number, a social security number, a UIN number, or a telephone number. 2.18 A foreign key is a primary key from one table placed into another table, to preserve relationships you create this. The key is called a foreign key in the table that received the key. The Manager ID being the foreign key in the project table and the Manager ID being the primary key in the manager table is another
Background image of page 1
This is the end of the preview. Sign up to access the rest of the document.

This note was uploaded on 04/13/2008 for the course INFO 328 taught by Professor Norton during the Spring '08 term at Texas A&M.

Ask a homework question - tutors are online