Primary Key:
A primary key in a
Example:
- Students in Universities are assigned a unique registration number.
- Therefore, in a STUDENT database table, the attribute “reg_no” acts as primary key.
Foreign Key:
Foreign key is a column in a relational database table which provides a relation between two tables. It provides a cross reference between tables by pointing to primary key of another table.
Example:
- In STUDENT database table, the attribute “reg_no” acts as primary key and in COURSE database table in which the student selects his or her course, the same “reg_no” acts as foreign key for the STUDENT table.
Many to One relationship:
When more than one record in a database table is associated with only one record in another table, the relationship between the two tables is referred as many to one relationship. It is also represented as M: 1 relationship.
One to Many relationships:
When one record in a database table is associated with more than one record in another table, the relationship between the two tables is referred as one to many relationships. It is also represented as1: M relationship. This is the opposite of many to one relationship.
CROW FOOT ERD:
The Crow Foot ERD is an Entity Relationship Diagram which is used to represent the cardinalities present in the basic ER diagram. It is used to represent the relationships present between two tuples or tables present in the database.
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Chapter 3 Solutions
Database Systems: Design, Implementation, & Management
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- Provide a description of the three unique data categories, as well as the methods that were used to acquire them?arrow_forward1. Organizational path is a formal business plan that outlines key business issues. True or False? 2. The columns of the table hold attributes of the data, and each record usually has a value for each attribute, making it easy to establish the relationships among the data points is known as the Relational database. True or False? 3. Planning phase develops project plan including task, resource and time frame. True or False?arrow_forwardWhere do data characteristics and data items stand in relation to one another? How does scope apply to an attribute?arrow_forward
- Contribution Format or Traditional Format should be utilized to identify relevant expenses when preparing income statements? Give a detailed description of your response. To back up your claim, provide an example that includes two revenue statements, one for absorption and one for variable costs.arrow_forwardFor Mercy's purposes, what is the significance of a specified data model in terms of the company's data needs and goals?arrow_forwardTo be deemed complete, a report must include all of the information included in the records of the underlying table on which it is based.True Falsearrow_forward
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