DBA Final

weak

A _____ entity has a primary key that is partially or totally derived from the parent entity in the relationship.

True

A subtype contains attributes that are common to all of its super types.

True

A trigger is procedural SQL code that is automatically invoked by the RDBMS upon the occurrence of a given data manipulation event.

False

A weak relationship exists if the primary key of the related entity contains at least one primary key component of the parent entity.

False

All SQL commands must be issued on a single line.

only once

Composite primary keys are particularly useful as identifiers of composite entities, where each primary key combination is allowed _____ in the M:N relationship.

Describe what metadata are and what value they provide to the database system.

Data about data that profile information on data characteristics and relationships. (Data Dictionary)

Provides that each entity has a unique value in a primary key

Define entity integrity. What are the two requirements to ensure entity integrity?

True

Denormalization produces a lower normal form.

Describe a dependency diagram and explain its purpose.

Dependcy diagram shows the relationship between two tables and their related columns

False

Dependencies that are based on only a part of a composite primary key are called transitive dependencies.

In a(n) _____ diagram, the arrows above the attributes indicate all desirable dependencies.

Dependency

True

Depending on the sophistication of the application development software, nulls can create problems when functions such as COUNT, AVERAGE, and SUM are used.

The end-user interface: Allows the user to interact with the data A collection of tables: All data is stored in table for a relational database SQL engine: executes all queries in the database

Describe the three parts involved in any SQL-based relational database application.

A total completeness constraint is represented by a _____.

Double horizontal line under a circle

Explain multivalued attributes with the help of examples. How are multivalued attributes indicated in the Chen Entity Relationship model?

Double line connecting the attribute to the entity

guaranteed access

Dr. Codd's _________ rule of relational database states that every value in a table is guaranteed to be accessible through a combination of table name, primary key value, and column name.

A relationship is an association between

Entities

participation

Failure to understand the distinction between mandatory and optional _____ in relationships might yield designs in which awkward (and unnecessary) temporary rows (entity instances) must be created just to accommodate the creation of required entities.

Dependencies that are based on only a part of a composite primary key are called transitive dependencies.

False

In a real-world environment, we must strike a balance between design integrity and _____.

Flexibility

False

In Chen notation, entities and relationships have to be oriented horizontally, not vertically.

crows foot

In _______, a three-pronged symbol represents the "many" sides of the relationship.

What is a key and how is it important in a relational model?

In a relational model, keys are important because they are used to ensure that each row in a table is uniquely identifiable. They are also used to establish relationships among tables and to ensure the integrity of the data. A key consists of one or more attributes that determine other attributes. For example, an invoice number identifies all of the invoice attributes, such as the invoice date and the customer name.

True

In an SQL-based relational database, rows in different tables are related based on common values in common attributes.

Network

In the _____ model, each parent can have many children, but each child has only one parent.

Explain the Boyce-Codd normal form (BCNF). How is it related to other normal forms?

It is third normal form that cannot have more than one candidate key

The organization of data within folders in a manual file system is determined by

Its expected use

True

Normalization works through a series of stages called normal forms.

True

One disadvantage of a database system over previous data management approaches is increased costs.

Within a specialization hierarchy, every subtype can have _____ super type(s) to which it is directly related.

Only one

What is a subquery? What is always executed first?

Query within a query. The sub most query gets executed first

True

Since a partial dependency can exist only if a table's primary key is composed of several attributes, if a table in 1NF has a single-attribute primary key, then the table is automatically in 2NF.

entity

The CUSTOMER table's primary key is CUS_CODE. The CUSTOMER primary key column has no null entries, and all entries are unique. This is an example of _____ integrity.

Count

The SQL aggregate function that gives the number of rows containing non-null values for a given column is _____.

Unique

The _____ specification is used to avoid having duplicated values in a column.

NOT NULL

The ______constraint can be placed on a column to ensure that every row in the table has a value for that column.

normalization

The combination of ______and ER modeling yields a useful ERD, whose entities may now be translated into appropriate table structures.

True

The entity relationship model (ERM) is dependent on the database type.

1980s

The object-oriented data model was developed in the

How are triggers critical to proper database operation and management?

Triggers allow for auto processing of data and keep the user from constantly having to monitor changes

Foreign

_____ work with primary keys to properly implement relationships in the relational model.

BCNF can be violated only if the table contains more than one _____ key

candidate

What do specialization hierarchies do?

depicts the arrangement of higher-level entity supertypes (parent entities) and lower-level entity subtypes (child entities).

data anomaly

develops when all required changes in the redundant data are not made successfully.

Database Management System (DBMS)

is a collection of programs that manages the database structure and controls access to the data stored in the database.

Granularity

refers to the level of detail represented by the values stored in a table's row.

Performance Tuning

relates to the activities that make the database execute transactions more efficiently in terms of storage and access speed.