Question

QUESTION 1 What is the most common relationship within a relational database? Select the best answer from the following. One-To-One relationship. o One-To-Many relationship. Many-To-Many relationship. Zero-To-Zero relationship. QUESTION 2 What is an "entity'? Select the best answer from the following. An entity, for our purposes, is the same as a table in the database. An entity represents one of the columns in an individual table. There are no entities in a relational database. Entities are only part of NoSQL databases. O An entity provides the meta-data about the entire database. QUESTION 3 What is true of foreign keys. Select the best answer from the following. A foreign key is a column or columns that is the same as the primary key of some table in the database. A foreign is created by giving it the same name as the column that it matches in the primary (parent) table. O A foreign key is only found in Many-To-Many relationships and is the mechanism that makes this relationship possible in database. Foreign keys are not used in relational database design

Answer 1

sol: The correct option with explainations is provided below:

1. Answer - Option 2) One-to-many relationship is the most common relationship in an ER diagram. The rest are not used as frequently as One-to-many.

2.Answer - Option 1) The term entity is usually used in place of a table. The table columns are attributes that an entity has. Entity does not represent the columns of table, the columns are the attributes of enitity. Entity are the most important part of a relational data base.

3.Answer-Option 1) A foreign key is a column or columns that refers to a primary key of some table. It can have any name but it should mention which table's primary key it is refering to. Foreign key can be found in all types of relationship because it is used to link two entities. It is another fundamnetal part of a relational database.

4.Answer- Option 4) Multivalued and single valued are both used in a relational database but single valued is more efficient because multivalued attributes slow down the search in a database. Multivalued attributes may or may not be used based on the requirement of the problem statement. For instance, phone number can be multivalued as a person may have more than one phone numbers.

5.Answer- Option 1,3,4) Primary key is the unique iderntifier of a row and thus cannot be null. It should be immutable as well and not changed once set. It is used to link one table to another via a foreign key.

7.Answer - Option 3) ERD refers to entity relationship diagram which shows the relationships of entites of a database.

8. Answer-Option 2) Attributes are the fields or columns of a table and a table is actually the entity of a database. Attributes are also an important part of Relational database and are used to provide information about each entity.

9. Answer-Option 4) Referential Integrity is enforced to maintain consistency among the references among tables. It prevents users from providing incorrect data.

NOTE: In the images question 6 is not provided, after question 5 there is question 7.

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