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
Technology
Daily Recommendation