Database Applications and Authorization
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Questions and Answers

What type of index contains an entry for every table row?

  • Bitmap index
  • Hash index
  • Sparse index
  • Dense index (correct)

    • Physical design of a database affects query results.

    False

    What is the purpose of a bitmap index?

    A bitmap index is a grid of bits used to efficiently store and retrieve data based on specific criteria.

    In a binary search, the database repeatedly splits the index until it finds the entry containing the ___.

    <p>search value</p> Signup and view all the answers

    Match the following types of indexes with their descriptions:

    <p>Hash index = Index entries are assigned to buckets Bitmap index = Grid of bits representing data presence Logical index = Facilitates access through logical structures Function index = Allows indexing based on function results</p> Signup and view all the answers

    What is an example of an entity instance?

    <p>The employee Sam Snead</p> Signup and view all the answers

    Cardinality refers only to the maximum relationship between entities.

    <p>False</p> Signup and view all the answers

    What is the primary function of analysis in entity-relationship modeling?

    <p>To capture data requirements while ignoring implementation details</p> Signup and view all the answers

    In entity-relationship modeling, a ______ is a set of related things.

    <p>relationship type</p> Signup and view all the answers

    Match the steps of analysis with their respective names:

    <p>Step 1 = Discover entities, relationships, and attributes Step 2 = Determine cardinality Step 3 = Distinguish strong and weak entities Step 4 = Create supertype and subtype entities</p> Signup and view all the answers

    Which of the following is NOT a step in logical design?

    <p>Create supertype and subtype entities</p> Signup and view all the answers

    An attribute instance is a statement about entity instances.

    <p>False</p> Signup and view all the answers

    Define what a subtype entity is.

    <p>A subset of another entity type, called the supertype entity.</p> Signup and view all the answers

    What is the purpose of creating supertype and subtype entities in database design?

    <p>To organize entities into hierarchical structures</p> Signup and view all the answers

    In crow's foot notation, cardinality is illustrated using circles and lines.

    <p>True</p> Signup and view all the answers

    What term describes the relationship that identifies a supertype-subtype connection?

    <p>IsA relationship</p> Signup and view all the answers

    A _____ key is created by the database designer when no suitable primary key exists.

    <p>artificial</p> Signup and view all the answers

    Which of the following is NOT a characteristic of a primary key?

    <p>Descriptive</p> Signup and view all the answers

    Match the following terms with their definitions:

    <p>Redundancy = The repetition of related values in a table Functional dependence = Dependence of one column on another Subtypes = Mutually exclusive groups of entities Crow's foot notation = A popular convention to depict cardinality</p> Signup and view all the answers

    What should primary key values be, according to database design principles?

    <p>Stable, simple, meaningless</p> Signup and view all the answers

    Artificial keys contain descriptive information to make them more intuitive.

    <p>False</p> Signup and view all the answers

    What does the SET NULL action do when a foreign key is invalid?

    <p>Sets invalid foreign keys to NULL</p> Signup and view all the answers

    The BETWEEN operator can only check for values that are strictly between two numbers.

    <p>False</p> Signup and view all the answers

    What is a subquery in SQL?

    <p>A query within another SQL query.</p> Signup and view all the answers

    In an entity-relationship model, an __________ is a descriptive property of an entity.

    <p>attribute</p> Signup and view all the answers

    Match the SQL actions with their descriptions:

    <p>SET NULL = Sets invalid foreign keys to NULL SET DEFAULT = Sets invalid foreign keys to the default value CASCADE = Propagates primary key changes to foreign keys CROSS JOIN = Combines two tables without comparing columns</p> Signup and view all the answers

    Which of the following statements is true regarding self-joins?

    <p>They involve joining a table to itself.</p> Signup and view all the answers

    Materialized views do not need to be refreshed after the base table changes.

    <p>False</p> Signup and view all the answers

    What does an entity-relationship diagram (ER diagram) represent?

    <p>Entities, relationships, and attributes in a schematic form.</p> Signup and view all the answers

    What is a characteristic of a candidate key?

    <p>It is unique and minimal.</p> Signup and view all the answers

    A table is considered to be in Boyce-Codd normal form if there are no non-key columns.

    <p>False</p> Signup and view all the answers

    What does normalization achieve in database design?

    <p>It eliminates redundancy by decomposing tables into higher normal forms.</p> Signup and view all the answers

    A __________ table imposes no order on rows and is optimized for insert operations.

    <p>heap</p> Signup and view all the answers

    Match the following table structures with their descriptions:

    <p>Heap table = No order on rows, optimized for inserts Sorted table = Physical row order determined by a sort column Hash table = Rows assigned to buckets using a hash function Table cluster = Interleaved rows from two or more tables</p> Signup and view all the answers

    When is a table said to be in third normal form?

    <p>Whenever a non-key column depends on a unique column.</p> Signup and view all the answers

    Denormalization is the process of eliminating redundancy in databases.

    <p>False</p> Signup and view all the answers

    Define what a trivial dependency is using an example.

    <p>A trivial dependency occurs when the columns of one set are a subset of another set, such as FareClass depending on (FlightCode, FareClass).</p> Signup and view all the answers

    Which of the following statements about data independence is true?

    <p>It allows reorganization of data on storage without affecting query results.</p> Signup and view all the answers

    The DROP TABLE statement can be used to delete a table but leaves its data intact.

    <p>False</p> Signup and view all the answers

    What SQL statement is used to add, delete, or modify columns in an existing table?

    <p>ALTER TABLE</p> Signup and view all the answers

    The data type for storing values with a specific number of characters is called ______.

    <p>VARCHAR(N)</p> Signup and view all the answers

    Match the following SQL commands with their functions:

    <p>CREATE TABLE = Creates a new table DROP TABLE = Deletes a table and its data ALTER TABLE = Modifies the structure of an existing table UPDATE = Changes existing records in a table</p> Signup and view all the answers

    Which data type would you use for a value that needs to store an integer up to 100?

    <p>TINYINT</p> Signup and view all the answers

    VARCHAR is used exclusively for integer storage in SQL.

    <p>False</p> Signup and view all the answers

    What is the signed range of SMALLINT data type?

    <p>-32,768 to 32,767</p> Signup and view all the answers

    The command ______ is used to change existing rows in a database table.

    <p>UPDATE</p> Signup and view all the answers

    Match the data types with their storage sizes:

    <p>TINYINT = 1 byte SMALLINT = 2 bytes INTEGER = 4 bytes BIGINT = 8 bytes</p> Signup and view all the answers

    What is the purpose of the modulo operator (%) in SQL?

    <p>To divide one number by another and return the integer remainder</p> Signup and view all the answers

    The INT data type can represent numbers up to 4,294,967,295 when unsigned.

    <p>True</p> Signup and view all the answers

    What type of data can a DECIMAL(M, D) store?

    <p>Numeric values with M total digits and D decimal places</p> Signup and view all the answers

    The ______ operator compares two values for equality.

    <p>=</p> Signup and view all the answers

    Which of the following describes the role of the ALTER TABLE statement?

    <p>To change the structure of an existing table.</p> Signup and view all the answers

    What is the main function of the physical design phase in database design?

    <p>To add indexes and specify table organization</p> Signup and view all the answers

    Which statement accurately describes data independence?

    <p>Query results remain unaffected by changes in physical design</p> Signup and view all the answers

    What differentiates a row from a tuple in the context of database tables?

    <p>A tuple is unnamed while a row has a defined name</p> Signup and view all the answers

    Which characteristic is specific to tables in relational database systems?

    <p>Tables do not impose any order on their rows</p> Signup and view all the answers

    Which of the following parts of a table contributes to its structural definition?

    <p>The column data types, which determine the kind of values stored</p> Signup and view all the answers

    What is the primary responsibility of a database administrator?

    <p>To secure the database system against unauthorized access</p> Signup and view all the answers

    Which function does the transaction manager serve within a database system?

    <p>It ensures that transactions are executed properly and restores consistency in case of failure</p> Signup and view all the answers

    What is a key feature of the query processor in a database system?

    <p>It optimizes queries to improve execution times</p> Signup and view all the answers

    Which data type would you use to store values that require both an integer and a decimal point?

    <p>DECIMAL</p> Signup and view all the answers

    What ensures that data is consistent with both structural and business rules within a database?

    <p>Rules enforced by the database system</p> Signup and view all the answers

    In what phase of database design are requirements specified without choosing a specific database system?

    <p>Analysis phase</p> Signup and view all the answers

    What function does the storage manager perform in a database system?

    <p>It translates high-level instructions to file-system commands</p> Signup and view all the answers

    What is the purpose of synchronization in a database system?

    <p>To ensure copies of data across multiple locations are kept consistent</p> Signup and view all the answers

    Which of the following correctly describes the main function of Data Definition Language (DDL)?

    <p>Defines the structure of the database.</p> Signup and view all the answers

    Which statement best describes a row in a relational database table?

    <p>An unnamed sequence of values corresponding to columns.</p> Signup and view all the answers

    Which of the following is NOT a sublanguage of SQL?

    <p>Data Definition Debugging (DDD)</p> Signup and view all the answers

    When referring to SQL keywords, which of the following examples can be classified as such?

    <p>SELECT, FROM, WHERE</p> Signup and view all the answers

    What defines a cell in a relational database table?

    <p>A specific column of a specific row.</p> Signup and view all the answers

    Which statement accurately describes a key difference between dense and sparse indexes?

    <p>A dense index is larger than a sparse index.</p> Signup and view all the answers

    Which of the following statements about literals in SQL is true?

    <p>Strings must be surrounded by single or double quotes.</p> Signup and view all the answers

    Which of the following best characterizes a table in a relational database?

    <p>A table has a name, fixed columns, and varying rows.</p> Signup and view all the answers

    What is the role of a storage engine in database management?

    <p>To translate query instructions into low-level commands.</p> Signup and view all the answers

    When creating an index in SQL, which of the following syntaxes is correct?

    <p>CREATE INDEX IndexName ON TableName (Column1, Column2);</p> Signup and view all the answers

    Data independence in databases primarily refers to which of the following?

    <p>The flexibility to modify the data structure without altering access methods.</p> Signup and view all the answers

    Which type of index utilizes a grid of bits to store entries?

    <p>Bitmap index</p> Signup and view all the answers

    How does physical design influence database performance?

    <p>It defines the structure of indexes and partitions.</p> Signup and view all the answers

    What does the CASCADE action do when a primary key is modified?

    <p>It propagates primary key changes to associated foreign keys.</p> Signup and view all the answers

    Which of the following accurately describes a self-join?

    <p>It joins a table to itself to relate data within the same table.</p> Signup and view all the answers

    In the context of entity-relationship models, what is an attribute?

    <p>A descriptive property of an entity.</p> Signup and view all the answers

    What is the primary purpose of the BETWEEN operator in SQL?

    <p>To check if a value falls between specified minimum and maximum values.</p> Signup and view all the answers

    What happens when the WITH CHECK OPTION clause is applied to a view?

    <p>Inserts or updates that do not meet filter criteria are rejected.</p> Signup and view all the answers

    What is the role of a reflexive relationship in an entity-relationship model?

    <p>It relates an entity to itself.</p> Signup and view all the answers

    What is a characteristic of materialized views in a database?

    <p>Data is stored and can become outdated if not refreshed.</p> Signup and view all the answers

    What is a typical result of violating a database constraint during data modification?

    <p>An error message is generated, explaining the violation.</p> Signup and view all the answers

    What characterizes a candidate key in database design?

    <p>It can consist of multiple columns but must be unique and minimal.</p> Signup and view all the answers

    Which statement accurately describes Boyce-Codd normal form?

    <p>It requires that every determinant be a candidate key.</p> Signup and view all the answers

    In which scenario is denormalization commonly employed?

    <p>To enhance query performance by reducing the number of joins.</p> Signup and view all the answers

    When is a database table considered to be in third normal form?

    <p>When all non-key columns depend on only one candidate key.</p> Signup and view all the answers

    What is the primary purpose of normalization in databases?

    <p>To eliminate redundancy by decomposing tables into higher normal forms.</p> Signup and view all the answers

    Which of the following best describes trivial dependencies?

    <p>Dependencies where all columns in one set are part of the other set.</p> Signup and view all the answers

    Which type of table structure optimizes insert operations by allowing for unordered row storage?

    <p>Heap table</p> Signup and view all the answers

    Which of the following statements correctly describes the concept of hit ratio?

    <p>It is the percentage of rows selected by a query.</p> Signup and view all the answers

    Study Notes

    Database Applications

    • Database applications are software that helps business users interact with database systems.
    • Users interact in various roles, including database administrators responsible for security.
    • Database administrators enforce procedures for user access and maintain system availability.
    • A database administrator ensures the database system is secure against unauthorized users, and enforces user access procedures.

    Database Authorization

    • Many database users should have restricted access to specific tables, columns, and rows.
    • Database systems provide authorization for individual users to access specific data.
    • Rules ensure data consistency based on structural and business standards.
    • For example, if data is copied to different locations, those copies must remain synchronized.

    Database Query Processor

    • The query processor interprets queries to plan actions that modify or retrieve data.
    • It develops and executes instructions on the database.
    • Query optimization is utilized to execute instructions efficiently.
    • Database sizes vary from megabytes to terabytes, requiring index-based location of data.
    • The query processor translates high-level queries into low-level file-system commands.

    Transaction Manager

    • Transactions are ensured to execute correctly and efficiently.
    • The transaction manager resolves issues arising from concurrent transactions.
    • It handles restoring the database to a consistent state after a transaction or system failure.
    • The transaction manager manages conflicts, and ensures proper transaction execution.

    NoSQL Database Example: MongoDB

    • MongoDB is an open-source NoSQL database.
    • SQL commands like INSERT, SELECT, UPDATE, and DELETE are used to manage data.
    • INSERT adds rows,
    • SELECT retrieves data,
    • UPDATE changes existing data, and
    • DELETE removes rows.
    • MongoDB databases are stored in a document-based format, unlike relational databases.

    SQL Data Types

    • SQL uses various data types to define column values.
    • INT stores integers.
    • DECIMAL handles fractional numbers.
    • VARCHAR represents text; its length is specified in parenthesis (e.g., VARCHAR(255)).
    • DATE stores year, month, and day.

    Database Design

    • Analysis phase specifies database requirements, representing them as entities, relationships, and attributes.
    • Logical design converts entities, relationships, and attributes into a specific database system's tables, keys, and columns.
    • Physical design defines how tables are organized on storage media, impacting query processing speed.
    • Considerations in physical design include indexes and storage media organization.

    SQL Sublanguages

    • SQL language is divided into five sublanguages:
      • Data Definition Language (DDL): defines database structure.
      • Data Query Language (DQL): retrieves database data.
      • Data Manipulation Language (DML): manipulates database data.
      • Data Control Language (DCL): controls database user access.
      • Data Transaction Language (DTL): manages database transactions.

    Database Tables

    • Tables organize relational database data.
    • Each table has a name, fixed columns, and variable rows of data.
    • Columns (fields) have a name and data type.
    • Rows (records) represent data values for each column, with each value belonging to a defined column type.

    SQL Statements (CREATE, DROP, ALTER)

    • CREATE TABLE: creates a new table.
    • DROP TABLE: removes a table.
    • ALTER TABLE: modifies an existing table.
    • These commands define and alter table structure.

    Data Types (Integer)

    • Integer data types store positive and negative whole numbers.
    • Various sizes exist (e.g., INT, SMALLINT, BIGINT), with varying storage sizes (bytes).

    SQL Operators (Arithmetic, Comparison)

    • Arithmetic: +, -, *, /, % (modulo).
    • Comparison: =, !=, <, <=, >, >=, BETWEEN.

    SQL Statements (UPDATE, DELETE)

    • UPDATE Statement: modifies table data.
    • DELETE Statement: removes rows from a table.
    • These commands manipulate existing data.

    Primary Key Constraint

    • Primary keys uniquely identify rows in a table.
    • Used frequently for identification.

    Data Integrity

    • Referential integrity ensures relationships between tables with correct data.
    • Violations lead to database error correction action.
    • Constraints for data manipulation are critical for maintaining data integrity in the database.

    SQL Functions

    • ABS(): finds the absolute value.
    • LOWER(): converts to lowercase.
    • TRIM(): removes leading and trailing spaces.
    • Other functions provide specific data retrieval and manipulation.

    Aggregate and Join Functions

    • Aggregate functions (e.g., COUNT, MIN, MAX) summarize data characteristics from multiple rows.
    • Joins combine data from two or more tables based on common columns. This combines data from related tables.

    Entity-Relationship Model

    • Entity-relationship model represents data entities, their relationships, and attributes.

    Indexing

    • Indexes provide faster data access, improving query performance.
    • Different types of indexes like hash index, bitmap index, function index are used.
    • Creating indexes is a crucial aspect of database optimization for faster query performance.

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    Database Application Study Guide PDF

    Description

    This quiz covers essential concepts of database applications, including user roles such as database administrators and their responsibilities regarding data security and access. It also explores the query processor's role in managing data requests and ensuring data consistency. Test your knowledge on these critical database topics.

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