Database test
- Question 1. Advantages of database:
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Reduce redundancy, consistency and integrity of data.
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Attributes are described in many different data files.
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Ability to appear inconsistent and inconsistent data.
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Appeared anomalous information.
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- Question 2. Anomalous information may:
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Consistent data and integrity.
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There are no conflicting information.
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Lack of information in storage.
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Reflect the true objective data.
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- Question 3. Users can access:
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The whole database
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Limit
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Part of the database
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Depends on access
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- Question 4. The DBMS (DataBase Management System) database management system is:
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Software system controls access strategies and database storage organizations.
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Create data structure corresponding to data model.
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Update, insert, remove or modify file level data.
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Ensure safety, data security and data integrity.
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- Question 5. Characteristics of a data model:
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Users have access at anytime, anywhere.
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Stability, simplicity, need to check for redundancy, symmetry and have a solid theoretical basis.
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Simple and unstructured data representation.
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Simple data model.
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- Question 6. When manipulating data manipulation language on hierarchical database:
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There is a high probability of information volatility.
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Ensure data independence
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Ensure data integrity.
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Ensure stability
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- Question 7. The structural characteristics of the network model are:
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Contains one - one, one - many and many - many links.
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Contains one-to-one and one-to-many links.
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Contains multiple links - one and one - many.
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- Question 8. In the network database, when adding new records:
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Ensure consistency and integrity of data.
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Excess information.
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Consistency and integrity of data is not guaranteed.
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Conflict of information.
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- Question 9. In the relational database model:
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The order of the columns is not important.
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The order of the rows is not important.
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The order of the rows is important.
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The order of columns is important.
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- Question 10. X is a subset of attributes, symbol X Ω, when and only if:
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For every attribute of Ω
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If A Ω, deduce A X.
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For every attribute of Ω, is also the property of X
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For every attribute of X is also the attribute of Ω
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- Question 11. X and Y are any two subsets of Ω. Then XY means:
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When the argument is the same, the function has many values.
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(r, s R) ((a X) (r (a) = s (a)) deduce (b Y) (r (b) = s (b))).
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A value of Y is determined by a value of X.
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(r, s R) (r (X) = s (X)) deduce r (Y) = s (Y)
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- Question 12. Which of the following dependencies is fully dependent:
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(Invoice number, customer code) Customer name
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(ID card number, employee code) Working process
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(Order number, class code) Student's full name.
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(Newspaper code, customer code) Price quote
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- Question 13. Which type of standard, name and address attributes does the relationship contain?
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Standard format 2NF
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Standard form 1NF, not 2NF
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Standard 3NF format
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Standard 2NF form, not 3NF
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