Systems Analysis and Design - Essay Example

ID # Candi Keys “A candi key is a column or multiple columns, which can describe the database record in unique form. A single relation can have multiple candidate keys” (Janssen). In this project the candidate that can be used to uniquely identify the records of the database are stock number, vehicle number and model. With these candidate keys, a user can uniquely identify the records of the database:Serial NumberCandidate Keys01Stock Number02 Vehicle Number03ModelPrimary Keys “A primary key is the key through which users can uniquely identify the each record of the relation.

In one relation there is only one primary key” (Chapple). In this project the primary key that can be used for the uniquely identification of whole record is stock number for stock relation, vehicle number for vehicle relation.Serial NumberPrimary Keys01Stock Number02 Vehicle NumberForeign Keys Foreign key is also a primary key but it can be used in other relation for collecting information. This is known as primary key (sybase). In this project the foreign keys that can be used are stock number, vehicle number and model:Serial NumberPrimary Keys01Stock Number02 Vehicle Number03ModelSecondary keys In a relation there are several options for the selection of primary keys.

In this scenario, the keys that are selected is known as primary key, and other keys are secondary keys and both of the these collectively known as secondary keys (programmerinterview.com). In this project following can be selected as the secondary keys.Serial NumberSecondary Keys01Stock Number02 Vehicle Number03Model Works CitedChapple, Mike. DATABASES CATEGORIES. 13 02 2015. .Janssen, Cory. Candidate Key. 13 02 2015. .programmerinterview.com. What is the definition of a secondary key? 13 2 2015. .sybase.

Foreign Key Example. 13 02 2015. .