Part 1: Total number of questions: 10
1
[
Single- choice questions] (5 points) The Test table has a column: test_data number(5,4), which of the following values can be added to the column ().
A.22.2
B.2222.2
C.2.2
D.222
Correct
The total score for this question is 5 points
2
[Single-choice questions] (5 points)
For the ROLLBACK command, the following accurate statement is: ()
A. Cancel the data modification operation that was just performed
B. Cancel the last COMMIT command
C. Cancel all data modifications since this login
D. Cancel to the point where the last submission or rollback operation was performed
Correct
The total score for this question is 5 points
3
[Single-choice question] (5 points) Among
the primary key characteristics of the table, the correct statement is: ()
A. A table can define multiple primary keys
B. Each column of the primary key must be unique
C. The column of the primary key can be null
D. The primary key can be defined at the table or column level.
Correct
The total score for this question is 5 points
4
[Single-choice question] (5 points)
Delete all the data in the emp table without submitting it. The following correct sentence is: ()
A. DELETE * FROM EMP B. DELETE
TABLE EMP
C. DELETE FROM EMP D.
TRUNCATE TABLE EMP is
correct
The total score of this question is 5 points
5
[Single-choice question] (5 points) What
is wrong in the following description of tables and views: ()
A. yl table does not exist, can not create a view
B. Delete does not affect the view of the data base tables
C. modification of the view ultimately to the base table
data D. view from multiple tables can
correct
this problem total score of 5
6
[True/True Questions] (5 points) The
use of indexes can increase the speed of the query, but the more indexes are not the better. ()
A. True
B. False
correct
The total score for this question is 5 points
7
[True and True] (5 points)
When using the add option of the alter table command to add a new attribute column to an existing table, the initial value of each row of the new column is null. ()
A. Wrong
B.
Right Correct
The total score for this question is 5 points
8
[True and True] (5 points) After the
serial number is defined, the current value of the sequence can be obtained with currval the first time it is used. ()
A. Wrong
B.
Right Correct
The total score for this question is 5 points
9
[True/True Questions] (5 points)
As a database object, the view does not contain any actual data. ()
A. True
B. False
correct
The total score for this question is 5 points
10
[True/Trump] (5 points)
The field of the unique constraint cannot be null ()
A. True
B. False
correct
The total score for this question is 5 points
