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Questions and Answers
Which of the following is the correct way to name a relation in the context model?
What type of relationship is allowed in the context model?
What additional information is included in the fully attributed model compared to the context model?
What data type is used to store a gender value of 'M' or 'F' in the physical model?
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Which of the following is not a step in the System Development Life Cycle (SDLC)?
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What is the primary focus of logical design in the context of database management systems?
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Which phase of the database management process involves creating special storage-related constructs to house end-user tables?
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What is a key aspect of physical design in databases that becomes more complex when data are distributed at different locations?
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During the testing and evaluation phase of database management, what is done in parallel with applications programming?
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In the context of system evolution, what is a crucial aspect of the operational and maintenance phase?
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Study Notes
Context Model
- A context model must have a singular and capitalized relation name.
- Relationships (cardinalities) and messages including the relationship are included.
- Many-to-Many (M:N) relationships are allowed in a context model.
Fully Attribute Model
- A fully attribute model includes everything mentioned in the context model and attributes.
- M:N relationships are resolved in a fully attribute model.
Physical Model
- The physical model is an exact implementation plan, including data type and data size.
- It depends on the DBMS (Database Management System) relation.
- VARCHAR2 (30) is similar to a String, but reserves a fixed number of blocks.
- Char(3) is used for characters like gender (M/F) and reserves a fixed number of blocks.
- Number(precision, scale) has a total number of digits (precision) and digits after the decimal (scale).
- Date includes all date formats.
System Development Life Cycle (SDLC)
- SDLC involves 6 stages: Planning, Analysis, Detailed System Design, Testing and Evaluation, Implementation, and Maintenance.
Planning
- Gathering information, research, brainstorming, surveys, etc. are involved in the planning stage.
Analysis
- Analyzing the situation, defining problems and constraints, objectives, and scope and boundaries are part of the analysis stage.
Database Design
- Database design involves identifying characteristics required and has two views: business view and designer view.
Conceptual Design
- Conceptual design must embody a clear understanding of the business and its functional areas.
- It ensures that all necessary data is included and unnecessary data is excluded.
Logical Design
- Logical design is critical to the information system's smooth operation and involves translating the conceptual design into an internal model for a selected DBMS.
- Advantages and disadvantages are carefully studied in logical design.
Physical Design
- Physical design involves selecting data storage and data access characteristics of the database.
- It depends on device types, data access methods, and DBMS.
Implementation
- Implementation involves creating special storage-related constructs to house end-user tables.
Testing and Evaluation
- Testing and evaluation involve loading data into the database, testing, and fine-tuning for performance, integrity, concurrent access, and security constraints.
Operation and Maintenance
- Operation and maintenance involve periodic maintenance, access permission assignment, and security audits.
Design Approaches
- Top-down design starts from identifying the relation and then the attributes (from big picture to small picture).
- Bottom-up design starts from attributes to relation (from tiny details to big picture).
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Description
Test your knowledge on database modeling concepts - from context model to physical model. Identify the naming conventions for relations, cardinalities, and attributes, and understand the resolution of M:N relationships.
