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37 Cards in this Set

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  • Back
What is an attribute?
a characteristic of an entity that describes the entity in some way
In a data model, when can a weak only exist?
only in relationships with other entities
Which type of logical relationship is being described when each region can have one or more salespeople and each salesperson can sell in one or more regions?
a many-to-many relationship
Should you use a normalized or a denormalized database for write-intensive databases?
normalized
What are the deliverable outputs of the logical design?
a logical object model, a logical data model, and a high-level UI design
What is the purpose of a primary key?
It uniquely identifies each row in a database table.
Which action(s) does Microsoft recommend for validating your logical design?
Review the use cases and usage scenarios.
In an ER diagram, how is a weak entity represented?
a rectangle with a double border
Should you use a normalized or a denormalized database in an online transaction processing(OLTP) system to capture historical transactional data?
denormalized
Which type of logical relationship would be used when each row from one table relates to only one row from a second table and vice versa?
a one-to-one relationship
Should you use a normalized or a denormalized database for read-intensive databases?
denormalized
What is normalization?
the process of eliminating data redundancy in a database design
Why would it be beneficial to create a proof of concept?
to verify that a project is possible and to reduce the risk of project failure
Which type of logical relationship would be used when each row from one table relates to one or more rows from a second table?
a one-to-many relationship
How must your data be normalized to be in third normal form (3NF)?
The database must be in second normal form and NOT have a non-key column depend on another non-key column.
In an ER diagram, what does a circle at the end of a relationship line represent?
that the relationship is optional
In a logical data model, which database element represents an entity?
a table
In an ER diagram, how do you represent the many sides of a relationship line?
using a crow's foot
Which type of logical relationship can only be physically implemented using a junction table?
a many-to-many relationship
Is a cascading constraint necessary to enforce data integrity?
No. While you might want to cascade updates or deletes, you could prevent them altogether, so this is not required.
To what does the term "cardinality" refer?
the number of instances of one entity that can or must be associated with each instance of a second entity
How is having no data redundancy beneficial to your database?
It ensures data integrity.
What are the benefits of choosing the most appropriate data type for a data element in a database?
Selecting the most appropriate data type assists with data validation and optimizes storage in the database.
What is the purpose of a foreign key?
It establishes and enforces a relationship between the data in two database tables.
How can you ensure your database is in second normal form (2NF)?
The database must be in first normal form and have every non-key column depend on the entire primary key.
Which type of integrity ensures values for a given column are valid?
domain integrity
Which guidelines should you follow to optimize the use of transactions?
Each transaction should be as short-lived as possible, include only what is required, and if possible not be distributed.
In an ER diagram, how is a regular entity represented?
a rectangle with a single border
When determining the level of normalization for a database, what is the recommended maximum number of tables that should be used in a frequent query?
4
What should you do if you want the data in two columns to uniquely identify each row?
Create a composite, primary key using the two columns.
How is it beneficial to queries in your database to have denormalized tables?
It optimizes queries. Because fewer joins are necessary, queries are usually faster.
What is a federated database?
a database that is partitioned into different instances and can run on different physical machines
Which term refers to the logical connection between two entities?
relationship
How can you ensure your database is in first normal form (1NF)?
Ensure it has no repeating groups or multi-values columns.
How should you design a junction table to implement a many-to-many relationship between two tables?
You should create a composite primary key for the junction table that consists of the primary keys from the other two tables. You can also add any other columns to the junction table that are needed.
What is denormalization?
Denormalization is the process of including redundancy in a database design, usually to improve performance. Denormalization results in tables with fewer fields requiring fewer joins.
How is having indexed columns beneficial to your database?
It allows for faster queries and faster sorting.