Concept explainers
Given Crow Foot Relational Diagram:
Primary Key:
A Primary Key in a database table is a field in the table that uniquely identifies every row or record present in the database table.
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.
One to Many Relationship:
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 relationship. It is also represented as1: M relationship. This is the opposite of many to one relationship.
Many to Many Relationship:
When more than 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 many to many relationship. This is represented as m: n relationship where m and n are two entities.
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
- Using normalisation principles, depict the relationship schema of the 3NF tables. State the respective primary keys.arrow_forwardUsing the Entity Relationship Diagram you have created, create the tables and insert the values supplied in each table. Make use of MYSQLarrow_forwardDo the tables in figure 1 exhibit entity referential integrity? Why or why not?arrow_forward
- Describe the relationships(identify the business rules) depicted in the Crow's Foot ERD shown in Figure P2.13arrow_forwardDescribe the relationships (identify the business rules) depicted in the Crow’s Foot ERD shown in Figure P2.13.arrow_forwardhow to translate the shown ER Diagram to a relational schema?arrow_forward
- Need help translating this ER diagram into the appropriate relational schemas.arrow_forwardQuestion 1 Show the relationships between entities and use table bridges between entities if necessary.arrow_forwardConsider the E-R diagram in Figure 8.9, which contains specializations, usingsubtypes and subtables. Give an SQL schema definition of the E-R diagram.arrow_forward
- A.What characteristics do tables that conform to the concept of well-informed relations have? B Describe a dependency diagram and explain its purpose C. Normalize the relation given below OrderNum OrderDate PartNumber PartName UnitPrice PartQuantity SupplierNumber SupplierName SupllierStreet SupplierCity SupplierSate SupplierZiparrow_forwardUsing any application of your choice, create an interactive presentation explaining the differences between various types of relationships between tables in an enterprise relationship diagram (ERD).arrow_forwardDesign the Facebook DB Schema using necessary Entity Relationshipsarrow_forward
- Database Systems: Design, Implementation, & Manag...Computer ScienceISBN:9781285196145Author:Steven, Steven Morris, Carlos Coronel, Carlos, Coronel, Carlos; Morris, Carlos Coronel and Steven Morris, Carlos Coronel; Steven Morris, Steven Morris; Carlos CoronelPublisher:Cengage LearningDatabase Systems: Design, Implementation, & Manag...Computer ScienceISBN:9781305627482Author:Carlos Coronel, Steven MorrisPublisher:Cengage Learning