Assignment 1
Q 1: the purpose of a database system with example. (10 Explain 3 points of your choice of
points)
Answer:
1. Data Redundancy and Inconsistency:
Explanation: A database system reduces unnecessary data duplication and ensures consistent
information across the system.
Example: In a traditional file system, if a customer’s address is stored in multiple places and only one is
updated, it leads to inconsistencies. A database centralizes the information, preventing this issue.
2. Retrieving Data:
Explanation: Databases allow users to efficiently query and retrieve specific data.
Example: A librarian can quickly find all books by a particular author by querying the database, rather
than searching through physical files.
3. Updating Data:
Explanation: Databases ensure that when data is updated, all related information remains consistent.
Example: If a customer updates their address in an online store’s database, future shipments will
automatically go to the correct address.
Q 2: Explain the instances and schemas in relational data model. (8 Points)
Answer:
A schema defines the structure of the database, including tables, columns, data types, and relationships.
It’s like a blueprint that specifies how the data is organized and managed.
• Physical Schema: Describes the physical storage of data, detailing how the data is stored on the
hardware.
• Logical Schema: Describes the logical structure, such as tables and relationships, without considering
how data is stored.
An instance is the actual data stored in the database at a specific moment in time. It reflects the current
state of the data that adheres to the schema’s structure.
Q3: Explain what DDL and DML are for DBMS. (8 Points)
Answer:
DDL is used to define and manage the structure of a database, such as creating tables, specifying keys,
and setting up constraints. When DDL commands are executed, they generate templates that are stored
in a data dictionary.
DML is used for querying and modifying data within the database. It's also known as a query language
and comes in two main types.
• Procedural DML: Specifies what data is needed and how to get it.
• Declarative DML: Specifies what data is needed without detailing how to retrieve it.
Q4: Explain two-tier and three-tier application architectures of database applications. (4 Points)
Answer:
In two-tier architecture, the application runs on the client machine, which directly communicates with
the database on the server. The client handles the user interface and business logic, while the server
manages database access.
In three-tier architecture, the client (front end) interacts with an application server (middle tier), which
in turn communicates with the database server (back end). The client handles the user interface, while
the application server manages business logic and database interactions.
Formatting
In a Word/PDF document, please attach screenshots for each task mentioned above to earn full
points.
How to Submit
• After you complete the assignment in Word (or another platform), you will want to make
sure it is saved as a .docx or .pdf
• Click "Start Assignment" in the upper right-hand corner
• Click "Upload Document"
• After your document is uploaded, click "Submit Assignment" below the box where you
upload your document.
• Deadline: 11:59 pm of Wednesday 09/04/2024. (1 labor day counted.)
Late Work
• An assignment that is turned in no more than 24 hours late will be scored with a 10%
penalty.
• An assignment that is turned in no more than 48 hours late will be scored with a 20%
penalty.
• An assignment that is turned in more than 48 hours late will receive a score of zero.
