Information Systems for Business and Beyond (2019)

takes two or more courses, then his or her data would have to be entered twice or more times. This means the data are redundant. Instead, the designers solved this problem by introducing the GRADE table. In this design, when a student registers into the school system before taking a course, we first must add the student to the STUDENT table, where their ID, name, major, and e-mail address are entered. Now we will add a new entry to denote that the student takes a specific course. This is accomplished by adding a record with the StudentID and the CourseID in the GRADE table. If this student takes a second course, we do not have to duplicate the entry of the student’s name, major, and e-mail; instead, we only need to make another entry in the GRADE table of the second course’s ID and the student’s ID. The design of the School database also makes it simple to change the design without major modifications to the existing structure. For example, if the design team were asked to add functionality to the system to track instructors who teach the courses, we could easily accomplish this by adding a PROFESSOR table (similar to the STUDENT table) and then adding a new field to the COURSE table to hold the professors’ ID. Data Types When defining the fields in a database table, we must give each field a data type. For example, the field StudentName is text string, while Enrollment Capacity is number. Most modern databases allow for several different data types to be stored. Some of the more common data types are listed here: • Text: for storing non-numeric data that is brief, generally under 256 characters. The database designer can identify the maximum length of the text. • Number: for storing numbers. There are usually a few different number types that can be selected, depending on Information Systems for Business and Beyond (2019) pg. 74

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