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Catégorie :Category: nCreator TI-Nspire
Auteur Author: SPITZER2001
Type : Classeur 3.0.1
Page(s) : 1
Taille Size: 3.97 Ko KB
Mis en ligne Uploaded: 20/11/2024 - 17:05:36
Uploadeur Uploader: SPITZER2001 (Profil)
Téléchargements Downloads: 10
Visibilité Visibility: Archive publique
Shortlink : https://tipla.net/a4329799
Type : Classeur 3.0.1
Page(s) : 1
Taille Size: 3.97 Ko KB
Mis en ligne Uploaded: 20/11/2024 - 17:05:36
Uploadeur Uploader: SPITZER2001 (Profil)
Téléchargements Downloads: 10
Visibilité Visibility: Archive publique
Shortlink : https://tipla.net/a4329799
Description
Fichier Nspire généré sur TI-Planet.org.
Compatible OS 3.0 et ultérieurs.
<<
SQL Concepts and Query Functions What is the purpose of the COUNT function in the SQL statement? Answer: COUNT is an aggregate function used to count the number of orders for a particular customer. What is the purpose of the GROUP BY command in this SQL statement? Answer: GROUP BY groups orders by LastName, returning the count of orders for each customer. What is the purpose of the HAVING command in this SQL statement? Answer: HAVING filters groups by a condition, displaying only customers with more than 18 orders. How would you modify this SQL query to show orders for customers named Smith? Answer: Remove HAVING and add AND LastName = 'Smith' to the WHERE clause. What is the meaning of LIKE '%0%0%'? Answer: Searches for values with two 0s in any position. Relational Database Design Principles Explain the concept of redundancy in a relational database and give an example. Answer: Redundancy means unnecessary duplication of data. Example: A Rents relationship is redundant if customers and rentals can be linked through the Rental entity. Explain what a deletion anomaly is in a database. Answer: It occurs when deleting a record causes loss of valuable information. Example: Deleting a student removes activity price details if activities aren't stored separately. What is meant by the term superkey? Answer: A superkey uniquely identifies a tuple and may include unnecessary attributes. What is meant by the term candidate key? Answer: A candidate key is a minimal superkey with no superfluous attributes, uniquely identifying tuples. Identify FIVE properties a relation must have in the relational model. Answer: Unique relation name. Atomic (single) values in cells. Unique attribute names. Consistent attribute domains. No duplicate rows. Database Design Phases What is the main purpose of conceptual database design? Answer: To investigate data needs independently of any specific model, identifying entities and attributes. What are the main features of logical database design? Answer: Designing data in the chosen model, including normalization, ER modeling, and attribute definition. Referential Integrity and Constraints What is referential integrity? Give an example. Answer: Ensures foreign keys match candidate keys in the parent table. Example: An Orders CustomerID must exist in the Customer table. What is meant by a propagation constraint? Give an example. Answer: Rules for changes in referenced data. Example: If a Customer is deleted, their Orders may be deleted (cascade) or set to null. Describe FOUR options for propagation constraints in a database. Answer: No Action: No changes in dependent table. Cascade: Propagate changes. Set Default: Set a default value. Set Null: Set the foreign key to null. Database Operations and Transactions Distinguish between database transactions and operations with an example. Answer: Operations are individual actions (e.g., CREATE, UPDATE). Transactions are composed of multiple operations (e.g., placing an order involves creating rows in multiple tables). Identify FOUR aspects that affect database transaction performance. Answer: Tables and columns accessed. Columns in search conditions. Join conditions. Frequency of transaction. How might the use of an index affect database operations? Answer: Improves query performance but may slow updates and insertions. Indexes and Derived Data Factors to consider when choosing columns to index: Answer: Columns used in joins. Columns frequently queried. Columns used for sorting. Factors to consider when storing derived data in a database: Answer: Complexity of calculations. Impact of table joins on performance. Frequency of updates to derived attributes. Distributed Databases Describe FIVE advantages of implementing a distributed database. Answer: Mirrors organizational structure. Greater control. Improved availability. Enhanced reliability. Better performance and easier growth. Describe the principle of transparency in distributed databases. Answer: Local autonomy with no central reliance, supporting replication or fragmentation as needed. Relationships and Entity Modeling Possible many-to-many relationship in a repair garage scenario: Answer: Mechanics and vehicles, as each mechanic can work on multiple vehicles and vice versa. Representation of entities in ER diagrams: Answer: Entities are represented by rectangles. Relational Schema Design Properties Can a table in 1NF violate 2NF? Why? Answer: Yes, if a non-key attribute depends only on part of a composite key. Use of null values in relational schemas: Answer: Avoided in good schemas to ensure consistency and reduce redundancy. What SQL structure limits column values? Answer: The CHECK constraint. Is grouping many attributes into one table good schema design? Answer: No, it leads to redundancy and update anomalies; normalization is preferred. Made with nCreator - tiplanet.org
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Compatible OS 3.0 et ultérieurs.
<<
SQL Concepts and Query Functions What is the purpose of the COUNT function in the SQL statement? Answer: COUNT is an aggregate function used to count the number of orders for a particular customer. What is the purpose of the GROUP BY command in this SQL statement? Answer: GROUP BY groups orders by LastName, returning the count of orders for each customer. What is the purpose of the HAVING command in this SQL statement? Answer: HAVING filters groups by a condition, displaying only customers with more than 18 orders. How would you modify this SQL query to show orders for customers named Smith? Answer: Remove HAVING and add AND LastName = 'Smith' to the WHERE clause. What is the meaning of LIKE '%0%0%'? Answer: Searches for values with two 0s in any position. Relational Database Design Principles Explain the concept of redundancy in a relational database and give an example. Answer: Redundancy means unnecessary duplication of data. Example: A Rents relationship is redundant if customers and rentals can be linked through the Rental entity. Explain what a deletion anomaly is in a database. Answer: It occurs when deleting a record causes loss of valuable information. Example: Deleting a student removes activity price details if activities aren't stored separately. What is meant by the term superkey? Answer: A superkey uniquely identifies a tuple and may include unnecessary attributes. What is meant by the term candidate key? Answer: A candidate key is a minimal superkey with no superfluous attributes, uniquely identifying tuples. Identify FIVE properties a relation must have in the relational model. Answer: Unique relation name. Atomic (single) values in cells. Unique attribute names. Consistent attribute domains. No duplicate rows. Database Design Phases What is the main purpose of conceptual database design? Answer: To investigate data needs independently of any specific model, identifying entities and attributes. What are the main features of logical database design? Answer: Designing data in the chosen model, including normalization, ER modeling, and attribute definition. Referential Integrity and Constraints What is referential integrity? Give an example. Answer: Ensures foreign keys match candidate keys in the parent table. Example: An Orders CustomerID must exist in the Customer table. What is meant by a propagation constraint? Give an example. Answer: Rules for changes in referenced data. Example: If a Customer is deleted, their Orders may be deleted (cascade) or set to null. Describe FOUR options for propagation constraints in a database. Answer: No Action: No changes in dependent table. Cascade: Propagate changes. Set Default: Set a default value. Set Null: Set the foreign key to null. Database Operations and Transactions Distinguish between database transactions and operations with an example. Answer: Operations are individual actions (e.g., CREATE, UPDATE). Transactions are composed of multiple operations (e.g., placing an order involves creating rows in multiple tables). Identify FOUR aspects that affect database transaction performance. Answer: Tables and columns accessed. Columns in search conditions. Join conditions. Frequency of transaction. How might the use of an index affect database operations? Answer: Improves query performance but may slow updates and insertions. Indexes and Derived Data Factors to consider when choosing columns to index: Answer: Columns used in joins. Columns frequently queried. Columns used for sorting. Factors to consider when storing derived data in a database: Answer: Complexity of calculations. Impact of table joins on performance. Frequency of updates to derived attributes. Distributed Databases Describe FIVE advantages of implementing a distributed database. Answer: Mirrors organizational structure. Greater control. Improved availability. Enhanced reliability. Better performance and easier growth. Describe the principle of transparency in distributed databases. Answer: Local autonomy with no central reliance, supporting replication or fragmentation as needed. Relationships and Entity Modeling Possible many-to-many relationship in a repair garage scenario: Answer: Mechanics and vehicles, as each mechanic can work on multiple vehicles and vice versa. Representation of entities in ER diagrams: Answer: Entities are represented by rectangles. Relational Schema Design Properties Can a table in 1NF violate 2NF? Why? Answer: Yes, if a non-key attribute depends only on part of a composite key. Use of null values in relational schemas: Answer: Avoided in good schemas to ensure consistency and reduce redundancy. What SQL structure limits column values? Answer: The CHECK constraint. Is grouping many attributes into one table good schema design? Answer: No, it leads to redundancy and update anomalies; normalization is preferred. Made with nCreator - tiplanet.org
>>
