Kiểm Tra 1 Tiết - Tin Học 12

The given original data consists of 7 occurrences of the letter B, followed by 10 occurrences of the letter A, and finally 4 occurrences of the letter C. The compressed version of this data would represent the number of occurrences followed by the letter itself. Therefore, the correct answer is "7B10A4C".

The correct answer is "Phục vụ việc kết xuất thông tin từ nhiều bảng." This is because creating links between tables allows for the extraction of information from multiple tables. By establishing relationships between tables, data can be combined and queried across different tables, enabling more comprehensive and complex analysis.

The given original data is "BBBBAAAAAACCCCC". The compressed form of this data is "4B6A5C". This means that there are 4 consecutive occurrences of the letter B, followed by 6 consecutive occurrences of the letter A, and finally 5 consecutive occurrences of the letter C.

The program will use the username and password to identify the accessing object. This is a common method of authentication used in many systems and applications. The username and password combination acts as a form of credentials that the user must provide in order to gain access to the program. This method is widely used because it provides a simple and effective way to verify the identity of the user.

The correct answer is "Thêm, xóa, chỉnh sửa bản ghi" (Adding, deleting, modifying records). This is because updating data in a relational database involves performing operations such as adding new records, deleting existing records, and modifying the values of existing records. These operations allow for the manipulation and maintenance of the data stored in the database.

The correct answer is "Giảm dung lượng lưu trữ và tăng cường tính bảo mật." This is because data compression reduces the size of data, making it easier to store and transmit. Additionally, data compression can also enhance security by minimizing the amount of sensitive information that is stored or transmitted, reducing the risk of unauthorized access or data breaches.

The correct answer is "Tất cả các yếu tố" (All factors). When considering a database design, it is important to consider all aspects such as data constraints, database structure, and operations. Each of these factors plays a crucial role in ensuring the efficiency, integrity, and functionality of the database system. Therefore, it is necessary to take into account all these elements when examining a database design.

When working with a relational database, we can perform tasks such as sorting, querying, viewing data, and generating reports. These tasks involve organizing the data, searching for specific information, and presenting it in a meaningful way. Therefore, the answer "Sắp xếp, truy vấn, xem dữ liệu, kết xuất báo cáo" accurately describes the actions that can be performed when mining a relational database.

In a relational database, a "quan hệ" (relation) refers to a table. A table is a collection of rows and columns that stores data. It is used to organize and store related information in a structured manner. Therefore, the correct answer is "Bảng" (table).

The given answer "Nhập dữ liệu ban đầu" (Entering initial data) is not a step in creating a relational database. The other options listed are necessary steps in creating a relational database, such as selecting a primary key, naming and saving the table structure, and establishing relationships between tables.

The correct answer is "Người phân tích, thiết kế và người quản trị CSDL" because these individuals are responsible for analyzing, designing, and managing the database system. They are knowledgeable about the hardware and software components required for information security and system protection. They play a crucial role in implementing security measures and ensuring the confidentiality, integrity, and availability of information within the system.

The given answer is correct because it accurately describes the concept of a data model. A data model is a set of concepts that are used to describe the structure of data, the operations that can be performed on the data, and the constraints that apply to the data in a database. It is a mathematical model that defines objects and operations on those objects.

A relationship in a relational database typically has four main characteristics. These characteristics include the entity, which represents the object being modeled, the attributes, which describe the properties of the entity, the relationship itself, which defines the association between entities, and the cardinality, which specifies the number of instances of one entity that can be associated with another entity. These four characteristics are essential in designing and understanding the structure and behavior of a relational database.

The correct answer is "Truyền dữ liệu từ nơi lưu trữ đến nơi yêu cầu." (Transferring data from storage to the requested location) because this action is not related to exploiting or manipulating the data in a relational database. It is simply the process of moving data from one location to another. The other actions mentioned, such as sorting records, viewing data, and generating reports, are all typical operations used to extract and manipulate data in a relational database.

The correct answer is "Đọc một phần dữ liệu được phép" because Lazada is an e-commerce platform where buyers access data to view products and make purchases. Reading a portion of the data is allowed for the buyers to gather information about the products they are interested in.

The correct answer is "Các bộ là không phân biệt và thứ tự của các bộ là quan trọng". This statement is incorrect because in a relational database, tuples (bộ) are distinct and the order of tuples is not important.

The statement "CSDL tổ chức tốt là CSDL có ít bảng" is incorrect. A well-organized database does not necessarily mean it has fewer tables. The organization of a database depends on its design, normalization, and the relationships between tables. A well-designed database can have multiple tables that are properly structured and linked together to efficiently store and retrieve data. Therefore, the number of tables in a database does not determine its quality or organization.

The given answer states that there is a composite attribute in the given data table. A composite attribute is an attribute that can be divided into sub-attributes. In the given data table, it is not clear which specific attribute is considered composite. Therefore, it is difficult to provide a specific explanation for this answer without further information.

The given answer is incorrect. The correct answer is "Nên chọn khóa chính là khóa có ít thuộc tính nhất" (It is advisable to choose the primary key with the fewest attributes). The other options are correct:
- Khoá chính do người dùng chỉ định (The primary key is determined by the user)
- Khoá chính không được để trống (The primary key cannot be empty)
- Khoá chính có thể trùng nhau (The primary key can be duplicated)

The correct answer is "Đ". This answer suggests that students have the right to access and view their exam scores in the database.

The statement "Mọi người đều có thể truy cập, bổ sung và thay đổi bảng phân quyền" is incorrect. Not everyone should have access to modify or change the permission table. The permission table should be controlled and managed by authorized individuals to ensure the security and integrity of the database.

The term "Bộ" in the context of a relational database refers to a "Row" or a "Tuple". In a relational database, data is organized into tables, where each table consists of rows and columns. Each row represents a single record or instance of data, and it contains values for each column in the table. Therefore, "Bộ" is used to refer to a row in a table within the context of a relational database.

The statement "Trong một quan hệ, có thể tồn tại hai thuộc tính cùng tên" is incorrect. In a relation, each attribute must have a unique name. Having two attributes with the same name would violate the rules of a relational database.

The correct answer is "Nhập bằng mẫu hỏi" because it means "Enter by questionnaire" in English. This option suggests that data can be inputted into the table by using a questionnaire.

The correct answer is B1-B3-B2-B4. The explanation for this answer is that when creating a relational database, the first step is to create a table (B1). Then, the next step is to define the structure and attributes of the table and assign a name to it (B3). After that, we need to choose a primary key for the table (B2). Finally, we can establish relationships between tables (B4). Therefore, the correct order of the steps is B1-B3-B2-B4.

The correct answer is "CSDL được xây dựng trên mô hình dữ liệu quan hệ." This statement is true because a relational database is built on the relational data model, which organizes data into tables with rows and columns. The relationships between the tables are established through keys, such as primary keys and foreign keys. This allows for efficient storage, retrieval, and manipulation of data in a structured and organized manner.

The correct answer is "Hệ quản trị CSDL quan hệ" because it is the term used to refer to software used to create, update, and exploit relational databases. It is a system that manages the storage and retrieval of data in a structured format, allowing users to organize and manipulate data efficiently.

The explanation for the given answer is that the field SOBH (Số hiệu bảo hiểm) is chosen as the primary key because it is a numerical field, while the field HOTEN (Họ tên) is not. The primary key is usually a unique identifier for each record in a database table, and since it is not possible to have two records with the same insurance number (SOBH), it makes it a suitable choice for the primary key. On the other hand, it is possible to have multiple records with the same name (HOTEN), so it is not suitable for the primary key.

The correct answer is "Giảm dung lượng lưu trữ và tăng cường tính bảo mật." This option suggests that the system is used to reduce storage capacity and enhance security. It implies that the system helps in optimizing storage resources and protecting sensitive data from unauthorized access.

The correct answer is "Biểu mẫu" because a biểu mẫu (form) is commonly used to input data in a structured and organized manner, making it easier and faster to enter data and reducing the chances of errors. It provides a standardized format for collecting information and ensures consistency in data entry.

The statement "Người dùng phải có các giải pháp tốt về phần cứng và phần mềm để bảo mật thông tin, bảo vệ hệ thống" is correct because users need to have good hardware and software solutions to ensure the security of their information and protect their systems. This means having up-to-date antivirus software, firewalls, and other security measures in place to prevent unauthorized access and potential threats.

The correct answer is "Thứ tự các bộ không quan trọng" because in a relational database, the order of the tuples (rows) in a table does not matter. The database management system is responsible for organizing and retrieving the data efficiently, regardless of the order in which the tuples were inserted. Therefore, the order of the tuples does not affect the correctness or functionality of the database.

When creating a relational database, you do not add a set. The other options are valid actions that are typically performed when creating a database, such as naming attributes, adding a table, declaring attribute sizes, and specifying data types for attributes. However, adding a set is not a step involved in creating a relational database.

The given correct answer is "Mã hóa thông tin nhằm mục đích để đọc thông tin được nhanh và thuận lợi hơn." This statement is incorrect because the purpose of information encryption is not to make it easier and faster to read. Encryption is used to enhance data security by converting information into a format that is unreadable without the proper decryption key. It is not intended to make information more convenient or accessible.

The given table is not a relation because there are two records with the same value for the attribute "Mã số sách" as "TN - 013". This violates the primary key constraint, which states that each record in a relation must have a unique value for the primary key attribute. Therefore, the correct answer is "Một thuộc tính có tính đa trị" (A multi-valued attribute).

The correct answer is "Hiệu quả của bảo mật chỉ phụ thuộc vào hệ QTCSDL và chương trình ứng dụng." This statement is incorrect because the effectiveness of security also depends on the policies and awareness of information owners and users. It is not solely determined by the database management system and application program.

In a relational database, it is possible to have attributes with the same name in multiple different relations. This means that different relations can have attributes that share the same name, but they are distinct and separate from each other. This allows for flexibility and organization in the database design, as different relations can have similar attributes without causing conflicts or confusion.

The statement "Có thể chọn khóa chính là một trường bất kì của bảng" is incorrect. The primary key is a unique identifier for each record in a table, and it must be chosen carefully to ensure uniqueness and efficiency. It cannot be any arbitrary field in the table.

The correct answer is "Nhập dữ liệu cho bảng" because declaring the structure of a table does not involve inputting data into the table. It only involves naming the fields, declaring the field sizes, and selecting data types for the fields.

The action "Xem dữ liệu" (View data) does not involve updating or modifying the data. It simply allows the user to see the existing data without making any changes to it.