WGU C175 UPDATED EXAM SCRIPT QUESTIONS AND
SOLUTIONS RATED A+
✔✔Describe the ER model for "Each salesperson is authorized to sell to at least one or
many products, and each product can be sold by at least one or many salespeople." -
✔✔
✔✔"One salesperson backs-up another salesperson."
What is the name of this model? - ✔✔One-to-one unary relationship
✔✔"A salesperson manages zero to many other salespersons, and a salesperson is
managed by exactly one other salesperson."
What is the name of this model? - ✔✔One-to-many unary relationship
✔✔"A product can either be part of no other products or be part of several other
products, and a product can either be composed of no other products or be composed
of several other products."
What is the name of this model? - ✔✔Many-to-many unary relationship
✔✔What does 'refer' in Referential Integrity imply? - ✔✔This revolves around the
circumstance of trying to refer to data in one relation in the database, based on values
in another relation.
✔✔Define the delete rule RESTRICT. - ✔✔If the delete rule between two relations is
RESTRICT and an attempt is made to delete a record on the "one side" of the one-to-
many relationship, the system will forbid the delete to take place if there are any
matching foreign key values in the relation on the "many side".
✔✔Define the delete rule CASCADE. - ✔✔If the delete rule between two relations is
CASCADE and an attempt is made to delete a record on the "one side" of the
relationship, not only will the record be deleted but all of the records on the "many side"
of the relationship that have a matching foreign key value will also be deleted.
In other words, the delete will "cascade" from one relation to the other.
✔✔Define the delete rule SET-TO-NULL. - ✔✔If the delete rule between the two
relations is SET-TO-NULL and an attempt is made to delete a record on the "one side"
of the one-to-many relationship, that record will be deleted and the matching foreign key
values in the records on the "many side" of the relationship will be set to null.
, Essentially, it's exactly like the CASCADE delete option, but instead of completely
deleting all possible values, the values are set to NULL instead.
✔✔Which entity is uniquely identified by concatenating the primary keys of the two
entities it connects? - ✔✔Associative Entity
✔✔Which type of entity is also called a dependent entity? - ✔✔Weak Entity
✔✔Candidate Key - ✔✔This is when a relation has more than one attribute or minimum
group of attributes that represents a way of uniquely identifying the entity.
✔✔Concurrency Problem - ✔✔When two or more users are trying to update the same
record simultaneously.
✔✔Equijoin - ✔✔Combines two or more tables based on a column that is common to
the tables.
Example: Joining Client and Salesman tables that both contain the SalesmanID column
which have the exact same values.
✔✔Foreign Key - ✔✔When an attribute or group of attributes serves as the primary key
of one relation and also appears in another relation.
✔✔Natural Join - ✔✔Matches each row in a table against each row in another table
based on common values found in columns sharing a common name and data type.
✔✔Tuple - ✔✔Rows/records are referred to as tuples when talking about relations.
They serve the exact same function, it just has a different name in the context of
relations.
✔✔What are the five basic principles of The Database Concept? - ✔✔1. The creation of
a datacentric environment that is a significant company resource, which can be shared
inside and outside the company.
2. The ability to achieve data integration while storing data in a non-redundant fashion.
3. The ability to store data representing entities involved in multiple relationships w/o
introducing data redundancy.
4. Managing data control issues such as data security, backup and recovery, and
concurrency control.
5. High degree of data independence.
✔✔What are the four major DBMS approaches? - ✔✔- Hierarchical
- Network
- Relational
- Object-oriented
SOLUTIONS RATED A+
✔✔Describe the ER model for "Each salesperson is authorized to sell to at least one or
many products, and each product can be sold by at least one or many salespeople." -
✔✔
✔✔"One salesperson backs-up another salesperson."
What is the name of this model? - ✔✔One-to-one unary relationship
✔✔"A salesperson manages zero to many other salespersons, and a salesperson is
managed by exactly one other salesperson."
What is the name of this model? - ✔✔One-to-many unary relationship
✔✔"A product can either be part of no other products or be part of several other
products, and a product can either be composed of no other products or be composed
of several other products."
What is the name of this model? - ✔✔Many-to-many unary relationship
✔✔What does 'refer' in Referential Integrity imply? - ✔✔This revolves around the
circumstance of trying to refer to data in one relation in the database, based on values
in another relation.
✔✔Define the delete rule RESTRICT. - ✔✔If the delete rule between two relations is
RESTRICT and an attempt is made to delete a record on the "one side" of the one-to-
many relationship, the system will forbid the delete to take place if there are any
matching foreign key values in the relation on the "many side".
✔✔Define the delete rule CASCADE. - ✔✔If the delete rule between two relations is
CASCADE and an attempt is made to delete a record on the "one side" of the
relationship, not only will the record be deleted but all of the records on the "many side"
of the relationship that have a matching foreign key value will also be deleted.
In other words, the delete will "cascade" from one relation to the other.
✔✔Define the delete rule SET-TO-NULL. - ✔✔If the delete rule between the two
relations is SET-TO-NULL and an attempt is made to delete a record on the "one side"
of the one-to-many relationship, that record will be deleted and the matching foreign key
values in the records on the "many side" of the relationship will be set to null.
, Essentially, it's exactly like the CASCADE delete option, but instead of completely
deleting all possible values, the values are set to NULL instead.
✔✔Which entity is uniquely identified by concatenating the primary keys of the two
entities it connects? - ✔✔Associative Entity
✔✔Which type of entity is also called a dependent entity? - ✔✔Weak Entity
✔✔Candidate Key - ✔✔This is when a relation has more than one attribute or minimum
group of attributes that represents a way of uniquely identifying the entity.
✔✔Concurrency Problem - ✔✔When two or more users are trying to update the same
record simultaneously.
✔✔Equijoin - ✔✔Combines two or more tables based on a column that is common to
the tables.
Example: Joining Client and Salesman tables that both contain the SalesmanID column
which have the exact same values.
✔✔Foreign Key - ✔✔When an attribute or group of attributes serves as the primary key
of one relation and also appears in another relation.
✔✔Natural Join - ✔✔Matches each row in a table against each row in another table
based on common values found in columns sharing a common name and data type.
✔✔Tuple - ✔✔Rows/records are referred to as tuples when talking about relations.
They serve the exact same function, it just has a different name in the context of
relations.
✔✔What are the five basic principles of The Database Concept? - ✔✔1. The creation of
a datacentric environment that is a significant company resource, which can be shared
inside and outside the company.
2. The ability to achieve data integration while storing data in a non-redundant fashion.
3. The ability to store data representing entities involved in multiple relationships w/o
introducing data redundancy.
4. Managing data control issues such as data security, backup and recovery, and
concurrency control.
5. High degree of data independence.
✔✔What are the four major DBMS approaches? - ✔✔- Hierarchical
- Network
- Relational
- Object-oriented
