University Information Technology Foundation (Fujian Agriculture and Forestry University) Chapter 2023 Exam Answers are Superstar (Part Two)
5.5 Unit 5 Testing
1, multiple-choice questions When a student accesses and operates database records, the order of a record in the database has been adjusted, but the contents of the record have not changed. What impact do you think this operation will bring ()?
A, the order of records is not important. You can exchange them at will.
B, the order of the record is very important, can't change at will.
C, it will affect the query of records.
D, will change the meaning of the relationship
My answer: a.
2. Multiple-choice questions have the following three relational models: the foreign key of students' (student number, name, major) courses (course number, course name, credits) grades (student number, course number, grades) is ().
First, student number, class number, grade
B, student number, class number
C, student number, grades
D, class number, grades
My answer: B.
3. The following statement about redundant data is incorrect ().
A, should eliminate all redundant data in the database.
B, compared with the data processing system written in high-level language, the system written in relational database is easier to eliminate redundant data.
C, data backup is a common form of data redundancy, which can create backup files to prevent official files from being destroyed.
D, it is necessary to properly save some redundant data in the database, such as establishing a connection between two tables with the same attributes through * * * to provide data query and use.
My answer: a.
4. The integrity rule of the multi-choice relation model is a constraint condition for the relation. For example, the primary key attribute of all tuples in () integrity rule relationship cannot be empty. If there is a null value, the primary key value will not play the role of uniquely identifying the tuple.
I. Relationship
B, reference
C, user definition
D. entities
My answer: D.
5. Multiple choice questions in the relational model, in order to realize the connection between tables, the primary key of one table is usually put in another table as the link between data, and the attribute of this link is called foreign code. For example, in order to associate the following student table with the course selection table, the attribute () should be added to the course selection table as the external code (underlined part) of the table. Students (student number, name, gender, native place, age, class number) choose courses (_ _ _ _ _ _ _, course number, grades, remarks)
First, the student number
B. Name
C, gender
D, class number
My answer: a.
6. The data model of multiple-choice questions has great influence on database performance. A good data model should meet three requirements, including ().
Simulate the real world more realistically.
B, easy to understand
C, easy to realize on the computer
D, support multiple data compression formats
My answer: D.
7. Multiple choice questions in the relational model, the one-to-many relationship between tuples refers to ().
A, a field in a table can have multiple input values.
A record in one table can be associated with multiple records in another table.
A table can have multiple records.
A database can contain multiple tables.
My answer: B.
8. Multiple choice questions (), also known as information models, model data and information according to users' views.
A. Conceptual model
B, setting the model
C, machine model
D, abstract model
My answer: a.
9. Multiple choice questions In a relationship, the attribute set that can uniquely identify the entity is called ().
I. Scope
B. Contact person
C. primary keyword
D. foreign key
My answer: C.
10, multiple-choice questions A factory produces several products, each product is composed of different parts, and some parts can be used in different products, so the correct E-R diagram is ().