WGU D426 Data Management Foundations Study
Guide Notes with Complete Solutions | Graded A+ |
New 2025-2026 Update
D426 – Data Management Foundations Study Guide
INTRODUCTION TO DATABASES
1.1 Database Basics
• Data – numeric, textual, visual, or audio information that describes real-world systems. o Data
is collected and processed to aid in a variety of tasks, such as:
Forecasting weather
Analyzing financial investments
Tracking the global spread of pandemics o Data varies in several
important ways:
Scope – the amount of data produced and collected may vary.
Format – data may be produced as numbers, text, images, audio, and/or
video.
Access – some data sources are private while others are made publicly
online.
o Data today is digital – encoded as zeroes and one’s on electronic and magnetic
media.
o Data relationships are often represented in a graphical format, called a
visualization.
• Database – a collection of data in a structured format.
o The database structure ensures that similar data is stored in a standardized manner.
• Database System – AKA Database Management System (DBS) – software that reads and writes
data in a database.
o Database systems ensure data is secure, internally consistent, and available at all times. o
These functions are challenging for large databases with many users, making database
systems complex.
• Query – a request to retrieve or change data in a database.
• Query Language – a specialized programming language designed specifically for database
systems.
o Query languages read and write data efficiently, and differ significantly from
generalpurpose languages such as Python, Java, and C++.
,• Database Application – software that helps business users interact with database systems.
o Programmers write applications to simplify the user experience and ensure data access
is efficient and secure.
o Database software is organized in layers.
Applications interact with a query language on one layer, and a query language
interacts with a database system on another layer.
• Information Management System – a software application that managers corporate data for a
specific business function
o Usually includes a database system as well as other components, such as user interface,
business logic, and interfaces to other systems.
• Database Roles
o Database Administrator – responsible for securing the database system against
unauthorized users.
Enforces procedures for user access and database system availability.
o Database Designer – determines the format of each data element and the overall
database structure.
o Database Programmer – Develops computer programs that utilize a database. o
Database User – Consumer of data in a database.
,1.2 Database Systems
• File Systems and Database Systems o Large complex databases that are shared by many users
have special requirements:
Performance: when many users and applications simultaneously access large
databases, query response time degrades rapidly.
• Database systems maintain fast response times by structuring data properly on storage media
and processing queries efficiently.
Authorization: many database users should have limited access to specific tables,
columns, or rows of a database.
• Database systems authorize individual users to access specific data.
Security: database systems ensure authorized users only access permissible data.
• Database systems also protect against hackers by encrypting data and restricting access.
Rules: database systems ensure data is consistent with structural and business
rules.
Recovery: computers, database systems, and individual transactions
occasionally fail.
• Database systems must recover from failures and restore the database to a consistent state
without loss of data.
• Transactions o Transaction management is a challenging requirement for database systems.
o Transaction – a group of queries that must be either completed or rejected as a whole. o
Execution of some, but not all queries results in inconsistent or incorrect data.
o When processing transactions, database systems must:
Ensure transactions are processed completely or not at all.
When failing to process a transaction, the database system must reverse
partial results and restore the database to the values before the
transaction.
Prevent conflicts between concurrent transactions.
When multiple transactions access the same data at the same time, a
conflict may occur.
Ensure transaction results are never lost.
• Once a transaction completes, transaction results must always be saved on
storage media, regardless of application or computer failures.
• Architecture o The architecture of a database system describes the internal
components and the relationships between components.
At a high level, the components of most database systems are similar:
o The query processor - interprets queries, creates a plan to modify the database or
retrieve data and returns query results to the application.
The query processor performs query optimization to ensure the most efficient
instructions are executed on the data.
, o The storage manager – translates the query processor instructions into low level
filesystem commands that modify or retrieve data.
o The transaction manager - ensures transactions are properly executed.
Prevents conflicts between concurrent transactions.
Restores the database to a consistent state in the event of a transaction or
system failure.
o The log – is a file containing a complete record of all inserts, updates, and deletes
processed by the database.
The transaction manager writes log records before applying changes to the
database.
In the event of a failure, the transaction manager uses log records to restore the
database.
o The catalog – aka data dictionary – is a directory of tables, columns, indexes, and other
database objects.
• Database System Architecture o A database system is composed of:
A query processor
Storage manager
Transaction manager
Log and catalog o An application sends a query to the query processor.
o The query processor uses information in the catalog to perform query
optimization. o The storage manager translates the query processor instructions
into file-system commands and uses an index to quickly locate the requested data.
o The transaction manager logs inserts, updates, and delete queries, and the result is sent
back to the application.
o Metadata – data about the database, such as column names and the number of rows in
each table.
Database systems store metadata in the catalog and use metadata to process
queries.
• Products
o Most leading database systems are relational.
o Relational Database – stores data in tables, columns, and rows – similar to a
spreadsheet.
All data in a row represents a single object, such as a person, place, product, or
activity.
All relational database systems support SQL query language.
o SQL stands for - Structured Query Language and includes statements that read and write
data, create, and delete tables, and administer the database system.
o Relational systems are ideal for databases that require an accurate record of every
transaction.
o Open Source Software – software that anyone can inspect, copy, and modify with no
licensing fee.
Guide Notes with Complete Solutions | Graded A+ |
New 2025-2026 Update
D426 – Data Management Foundations Study Guide
INTRODUCTION TO DATABASES
1.1 Database Basics
• Data – numeric, textual, visual, or audio information that describes real-world systems. o Data
is collected and processed to aid in a variety of tasks, such as:
Forecasting weather
Analyzing financial investments
Tracking the global spread of pandemics o Data varies in several
important ways:
Scope – the amount of data produced and collected may vary.
Format – data may be produced as numbers, text, images, audio, and/or
video.
Access – some data sources are private while others are made publicly
online.
o Data today is digital – encoded as zeroes and one’s on electronic and magnetic
media.
o Data relationships are often represented in a graphical format, called a
visualization.
• Database – a collection of data in a structured format.
o The database structure ensures that similar data is stored in a standardized manner.
• Database System – AKA Database Management System (DBS) – software that reads and writes
data in a database.
o Database systems ensure data is secure, internally consistent, and available at all times. o
These functions are challenging for large databases with many users, making database
systems complex.
• Query – a request to retrieve or change data in a database.
• Query Language – a specialized programming language designed specifically for database
systems.
o Query languages read and write data efficiently, and differ significantly from
generalpurpose languages such as Python, Java, and C++.
,• Database Application – software that helps business users interact with database systems.
o Programmers write applications to simplify the user experience and ensure data access
is efficient and secure.
o Database software is organized in layers.
Applications interact with a query language on one layer, and a query language
interacts with a database system on another layer.
• Information Management System – a software application that managers corporate data for a
specific business function
o Usually includes a database system as well as other components, such as user interface,
business logic, and interfaces to other systems.
• Database Roles
o Database Administrator – responsible for securing the database system against
unauthorized users.
Enforces procedures for user access and database system availability.
o Database Designer – determines the format of each data element and the overall
database structure.
o Database Programmer – Develops computer programs that utilize a database. o
Database User – Consumer of data in a database.
,1.2 Database Systems
• File Systems and Database Systems o Large complex databases that are shared by many users
have special requirements:
Performance: when many users and applications simultaneously access large
databases, query response time degrades rapidly.
• Database systems maintain fast response times by structuring data properly on storage media
and processing queries efficiently.
Authorization: many database users should have limited access to specific tables,
columns, or rows of a database.
• Database systems authorize individual users to access specific data.
Security: database systems ensure authorized users only access permissible data.
• Database systems also protect against hackers by encrypting data and restricting access.
Rules: database systems ensure data is consistent with structural and business
rules.
Recovery: computers, database systems, and individual transactions
occasionally fail.
• Database systems must recover from failures and restore the database to a consistent state
without loss of data.
• Transactions o Transaction management is a challenging requirement for database systems.
o Transaction – a group of queries that must be either completed or rejected as a whole. o
Execution of some, but not all queries results in inconsistent or incorrect data.
o When processing transactions, database systems must:
Ensure transactions are processed completely or not at all.
When failing to process a transaction, the database system must reverse
partial results and restore the database to the values before the
transaction.
Prevent conflicts between concurrent transactions.
When multiple transactions access the same data at the same time, a
conflict may occur.
Ensure transaction results are never lost.
• Once a transaction completes, transaction results must always be saved on
storage media, regardless of application or computer failures.
• Architecture o The architecture of a database system describes the internal
components and the relationships between components.
At a high level, the components of most database systems are similar:
o The query processor - interprets queries, creates a plan to modify the database or
retrieve data and returns query results to the application.
The query processor performs query optimization to ensure the most efficient
instructions are executed on the data.
, o The storage manager – translates the query processor instructions into low level
filesystem commands that modify or retrieve data.
o The transaction manager - ensures transactions are properly executed.
Prevents conflicts between concurrent transactions.
Restores the database to a consistent state in the event of a transaction or
system failure.
o The log – is a file containing a complete record of all inserts, updates, and deletes
processed by the database.
The transaction manager writes log records before applying changes to the
database.
In the event of a failure, the transaction manager uses log records to restore the
database.
o The catalog – aka data dictionary – is a directory of tables, columns, indexes, and other
database objects.
• Database System Architecture o A database system is composed of:
A query processor
Storage manager
Transaction manager
Log and catalog o An application sends a query to the query processor.
o The query processor uses information in the catalog to perform query
optimization. o The storage manager translates the query processor instructions
into file-system commands and uses an index to quickly locate the requested data.
o The transaction manager logs inserts, updates, and delete queries, and the result is sent
back to the application.
o Metadata – data about the database, such as column names and the number of rows in
each table.
Database systems store metadata in the catalog and use metadata to process
queries.
• Products
o Most leading database systems are relational.
o Relational Database – stores data in tables, columns, and rows – similar to a
spreadsheet.
All data in a row represents a single object, such as a person, place, product, or
activity.
All relational database systems support SQL query language.
o SQL stands for - Structured Query Language and includes statements that read and write
data, create, and delete tables, and administer the database system.
o Relational systems are ideal for databases that require an accurate record of every
transaction.
o Open Source Software – software that anyone can inspect, copy, and modify with no
licensing fee.
