one . Single choice questions ( common 10 topic ,76 branch )

1. ( Single choice questions )

Established relationship WORK(ENO,CNO,PAY), The main code is (ENO,CNO). According to entity integrity rules (   )

* A.  only ENO Cannot take null value
* B.  only CNO Cannot take null value
* C.  only PAY Cannot take null value
* D. ENO And CNO Cannot take null value
My answer : D right key : D

7.6 branch

2. ( Single choice questions ) The following statement about primary key constraints is wrong ( )

* A. A. Only one primary key constraint can be set in a table
* B. B. Primary key constraints cannot be defined on fields that allow null values
* C. C. Primary key constraints can be defined on fields that allow null values
* D. D. You can set a field combination containing multiple fields as the primary key
My answer : C right key : C

7.6 branch

3. ( Single choice questions ) The significance of entity integrity constraint in relational database system lies in (        ).

* A. Uniquely identify tuples with primary keys
* B. Realize the connection between entities
* C. Prevent unauthorized access
* D. Ensure the security of relational computing
My answer : A right key : A

7.6 branch

4. ( Single choice questions ) following SQL Permissions in languages , Which allows the user to define a new relationship , Reference the primary code of other relationships as the foreign code ( ).

* A. INSERT 
* B. DELETE
* C.
REFERENCES

* D. SELECT
My answer : C right key : C

7.6 branch

5. ( Single choice questions ) Database (       )   It refers to the correctness and compatibility of data .

* A. A. Security
* B. B. Integrity
* C. C. concurrency control
* D. D. recovery
My answer : B right key : B

7.6 branch

6. ( Single choice questions ) Null value on attribute of primary key violates (   ).

* A.  Entity integrity rules
* B.  Referential integrity rules
* C.  Security rules
* D.  Model transformation rules
My answer : A right key : A

7.6 branch

7. ( Single choice questions ) stay SQL In the following statement , The statements that can implement entity integrity constraints are (   )

* A. FOREIGN KEY
* B. PRIMARY KEY
* C. REFERENCES
* D. FOREIGN KEY and REFERENCES
My answer : B right key : B

7.6 branch

8. ( Single choice questions )(    ) It is not a data control function that the database system must provide .

* A.  Security
* B.  Portability
* C.  Integrity
* D.  concurrency control
My answer : B right key : B

7.6 branch

9. ( Single choice questions ) Have the following relationship : student ( Student number , full name , Gender , Professional number , Age ), Define the value range of attribute age in 0-120 Match between (     )

* A.  Entity integrity
* B.  Referential integrity
* C.  User defined integrity
* D.  Logical integrity
My answer : C right key : C

7.6 branch

10. ( Single choice questions ) In the table definition of the database , Limit the value of performance attribute column in 0 reach 100 Within the scope of , Belonging to data (      ) constraint .

* A. A. Entity integrity
* B. B, Referential integrity
* C. C, User defined
* D. D, User operation
My answer : C right key : C

7.6 branch

two . Completion ( common 1 topic ,7.6 branch )

11. ( Completion ) Referential integrity of relational models ________ of use ________ The phrase defines which columns are foreign code columns , use ________ The phrase indicates which table primary codes these foreign codes refer to .

My answer :

5.1 branch

(1) CREATE TABLE 

(2) FOREIGN KEY 

(3) EFERENCES 

right key :

(1) CREATE TABLE

(2) FOREIGN KEY

(3) REFERENCES

three . Judgment question ( common 2 topic ,16.4 branch )

12. ( Judgment question ) In relationships , Candidate codes can be selected arbitrarily .(   )

* A. yes
* B. wrong
My answer :  Wrong or correct answer :  wrong

7.6 branch

13. ( Judgment question ) The external code can only take the value of the primary code of the referenced relationship .(  )

* A. yes
* B. wrong
My answer :  Wrong or correct answer :  wrong

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