Tricky TRUE OR FALSE DBMS QA
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Catégorie :Category: nCreator TI-Nspire
Auteur Author: SPITZER2001
Type : Classeur 3.0.1
Page(s) : 1
Taille Size: 4.33 Ko KB
Mis en ligne Uploaded: 20/11/2024 - 18:21:00
Uploadeur Uploader: SPITZER2001 (Profil)
Téléchargements Downloads: 11
Visibilité Visibility: Archive publique
Shortlink : https://tipla.net/a4329936
Type : Classeur 3.0.1
Page(s) : 1
Taille Size: 4.33 Ko KB
Mis en ligne Uploaded: 20/11/2024 - 18:21:00
Uploadeur Uploader: SPITZER2001 (Profil)
Téléchargements Downloads: 11
Visibilité Visibility: Archive publique
Shortlink : https://tipla.net/a4329936
Description
Fichier Nspire généré sur TI-Planet.org.
Compatible OS 3.0 et ultérieurs.
<<
Module 1: Introduction to DBMS True/False: "A DBMS can manage unstructured data natively without any schema definition." Justification: False. While NoSQL databases allow flexibility with schema, a schema is still defined implicitly or explicitly to understand the structure, even for unstructured data. True/False: "Isolation in ACID properties guarantees that every transaction will execute in sequence without overlapping." Justification: False. Isolation ensures that concurrent transactions do not interfere with each other, but they can still overlap using isolation levels like Read Committed or Serializable. Module 2: Data Models and ER Diagrams True/False: "An ER diagram with a many-to-many relationship between two entities can always be implemented without introducing an intermediate table." Justification: False. Many-to-many relationships must be resolved using an intermediate or junction table to maintain database normalization. True/False: "A weak entity can exist without a strong entity if its attributes are sufficiently unique." Justification: False. A weak entity depends on a strong entity for identification and cannot exist independently, regardless of attribute uniqueness. Module 3: SQL Basics True/False: "If the WHERE clause is not specified in a SELECT query, all rows from the table will be retrieved." Justification: True. Without a WHERE clause, there are no conditions to filter rows, so all rows are returned. True/False: "A query with a GROUP BY clause must always include an aggregate function like COUNT or SUM." Justification: False. A GROUP BY clause groups rows based on specified columns, but it is not mandatory to use aggregate functions with it. Module 4: Advanced SQL Techniques True/False: "A trigger that modifies the same table it is triggered on can cause a recursive loop and must always be avoided." Justification: False. Recursive triggers can be useful in specific scenarios but should be designed carefully to prevent infinite recursion or performance issues. True/False: "A query using a window function like RANK() cannot include an aggregate function like COUNT() in the same SELECT statement." Justification: False. Window functions and aggregate functions can coexist in the same query, but they serve different purposes and are evaluated differently. Module 5: Database Design and Normalization True/False: "A table in third normal form (3NF) automatically satisfies the requirements for first and second normal forms (1NF and 2NF)." Justification: True. 3NF includes the requirements of 1NF and 2NF, ensuring atomicity and eliminating partial dependencies. True/False: "Denormalization always improves performance by reducing the number of joins required for queries." Justification: False. While denormalization can improve read-heavy operations, it increases redundancy and the complexity of maintaining data consistency, which can hinder write-heavy workloads. Module 6: Database Implementation with Azure True/False: "Point-in-time recovery in Azure SQL Database can restore the database to a future state based on automated backups." Justification: False. Point-in-time recovery can only restore the database to a specific time in the past, not a future state. True/False: "Role-based access control (RBAC) in Azure allows fine-grained access at the row level within a database table." Justification: False. RBAC controls access at the database or resource level, not at the row level. Row-level security must be implemented separately. Module 7: DBMS with Python True/False: "In Pythons sqlite3 library, the execute() method can handle multiple SQL commands in a single call separated by semicolons." Justification: True. The execute() method can process multiple commands in one call if separated correctly, but caution is required to avoid SQL injection. True/False: "Using an ORM like SQLAlchemy removes the need to understand raw SQL syntax for database operations." Justification: False. While SQLAlchemy abstracts many operations, understanding SQL syntax is crucial for debugging complex queries or optimizing performance. General Advanced Questions True/False: "The TRUNCATE command in SQL can be rolled back if executed within a transaction block." Justification: False. TRUNCATE is a DDL command and is typically auto-committed, meaning it cannot be rolled back even within a transaction. True/False: "An index on a column with many duplicate values (low cardinality) can significantly improve query performance." Justification: False. Indexes are most effective for columns with high cardinality (many unique values), as they reduce the number of lookups required. True/False: "A stored procedure that performs multiple updates will always execute all updates if the first one succeeds." Justification: False. If the stored procedure includes a transaction and an error occurs mid-execution, the entire transaction, including previous updates, may be rolled back. True/False: "The UNION operator combines result sets
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Compatible OS 3.0 et ultérieurs.
<<
Module 1: Introduction to DBMS True/False: "A DBMS can manage unstructured data natively without any schema definition." Justification: False. While NoSQL databases allow flexibility with schema, a schema is still defined implicitly or explicitly to understand the structure, even for unstructured data. True/False: "Isolation in ACID properties guarantees that every transaction will execute in sequence without overlapping." Justification: False. Isolation ensures that concurrent transactions do not interfere with each other, but they can still overlap using isolation levels like Read Committed or Serializable. Module 2: Data Models and ER Diagrams True/False: "An ER diagram with a many-to-many relationship between two entities can always be implemented without introducing an intermediate table." Justification: False. Many-to-many relationships must be resolved using an intermediate or junction table to maintain database normalization. True/False: "A weak entity can exist without a strong entity if its attributes are sufficiently unique." Justification: False. A weak entity depends on a strong entity for identification and cannot exist independently, regardless of attribute uniqueness. Module 3: SQL Basics True/False: "If the WHERE clause is not specified in a SELECT query, all rows from the table will be retrieved." Justification: True. Without a WHERE clause, there are no conditions to filter rows, so all rows are returned. True/False: "A query with a GROUP BY clause must always include an aggregate function like COUNT or SUM." Justification: False. A GROUP BY clause groups rows based on specified columns, but it is not mandatory to use aggregate functions with it. Module 4: Advanced SQL Techniques True/False: "A trigger that modifies the same table it is triggered on can cause a recursive loop and must always be avoided." Justification: False. Recursive triggers can be useful in specific scenarios but should be designed carefully to prevent infinite recursion or performance issues. True/False: "A query using a window function like RANK() cannot include an aggregate function like COUNT() in the same SELECT statement." Justification: False. Window functions and aggregate functions can coexist in the same query, but they serve different purposes and are evaluated differently. Module 5: Database Design and Normalization True/False: "A table in third normal form (3NF) automatically satisfies the requirements for first and second normal forms (1NF and 2NF)." Justification: True. 3NF includes the requirements of 1NF and 2NF, ensuring atomicity and eliminating partial dependencies. True/False: "Denormalization always improves performance by reducing the number of joins required for queries." Justification: False. While denormalization can improve read-heavy operations, it increases redundancy and the complexity of maintaining data consistency, which can hinder write-heavy workloads. Module 6: Database Implementation with Azure True/False: "Point-in-time recovery in Azure SQL Database can restore the database to a future state based on automated backups." Justification: False. Point-in-time recovery can only restore the database to a specific time in the past, not a future state. True/False: "Role-based access control (RBAC) in Azure allows fine-grained access at the row level within a database table." Justification: False. RBAC controls access at the database or resource level, not at the row level. Row-level security must be implemented separately. Module 7: DBMS with Python True/False: "In Pythons sqlite3 library, the execute() method can handle multiple SQL commands in a single call separated by semicolons." Justification: True. The execute() method can process multiple commands in one call if separated correctly, but caution is required to avoid SQL injection. True/False: "Using an ORM like SQLAlchemy removes the need to understand raw SQL syntax for database operations." Justification: False. While SQLAlchemy abstracts many operations, understanding SQL syntax is crucial for debugging complex queries or optimizing performance. General Advanced Questions True/False: "The TRUNCATE command in SQL can be rolled back if executed within a transaction block." Justification: False. TRUNCATE is a DDL command and is typically auto-committed, meaning it cannot be rolled back even within a transaction. True/False: "An index on a column with many duplicate values (low cardinality) can significantly improve query performance." Justification: False. Indexes are most effective for columns with high cardinality (many unique values), as they reduce the number of lookups required. True/False: "A stored procedure that performs multiple updates will always execute all updates if the first one succeeds." Justification: False. If the stored procedure includes a transaction and an error occurs mid-execution, the entire transaction, including previous updates, may be rolled back. True/False: "The UNION operator combines result sets
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