Which view should a user query to disp...

单项选择题X 纠错

Which view should a user query to display the columns associated with the constraints on a table owned by the user?（）

A.USER_CONSTRAINTS
B.USER_OBJECTS
C.ALL_CONSTRAINTS
D.USER_CONS_COLUMNS
E.USER_COLUMNS

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LAST_NAME VARCHAR2(30) NOT NULL
FIRST_NAME VARCHAR2(30)
DEPT_ID NUMBER(2)
Which statement produces the number of different departments that have employees with last name Smith?（）

A.SELECT COUNT(*) FROM employees WHERE last_name='Smith';
B.SELECT COUNT(dept_id) FROM employees WHERE last_name='Smith';
C.SELECT DISTINCT(COUNT(dept_id)) FROM employees WHERE last_name='Smith';
D.SELECT COUNT(DISTINCT dept_id) FROM employees WHERE last_name='Smith';
E.SELECT UNIQUE(dept_id) FROM employees WHERE last_name='Smith';

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Which three statements about subqueries are true? （）

A.A single row subquery can retrieve only one column and one row.
B.A single row subquery can retrieve only one row but many columns.
C.A multiple row subquery can retrieve multiple rows and multiple columns.
D.A multiple row subquery can be compared using the ">" operator.
E.A single row subquery can use the IN operator.
F.A multiple row subquery can use the "=" operator.

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单项选择题

Click the Exhibit button and examine the data in the EMPLOYEES table.
On the EMPLOYEES table, EMPLOYEE_ID is the primary key. MGR_ID is the ID of managers and refers to the EMPLOYEE_ID. The JOB_ID column is a NOT NULL column.
Evaluate this DELETE statement:
DELETE employee_id, salary, job_id
FROM employees
WHERE dept_id = 90;
Why does the DELETE statement fail when you execute it?（）

A.There is no row with dept_id 90 in the EMPLOYEES table.
B.You cannot delete the JOB_ID column because it is a NOT NULL column.
C.You cannot specify column names in the DELETE clause of the DELETE statement.
D.You cannot delete the EMPLOYEE_ID column because it is the primary key of the table.

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Examine the description of the STUDENTS table:
STD_ID NUMBER(4)
COURSE_ID VARCHAR2(10)
START_DATE DATE
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A.SUM(start_date)
B.AVG(start_date)
C.COUNT(start_date)
D.AVG(start_date, end_date)
E.MIN(start_date)
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Examine the description of the MARKS table:
STD_ID NUMBER(4)
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SUBJ2 NUMBER(3)
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SELECT subj1+subj2 total_marks, std_id
FROM marks
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B.The statement returns an error at the SELECT clause.
C.The statement returns an error at the WHERE clause.
D.The statement returns an error at the ORDER BY clause.

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Examine the SQL statement that creates ORDERS table:
CREATE TABLE orders
(SER_NO NUMBER UNIQUE,
ORDER_ID NUMBER,
ORDER_DATE DATE NOT NULL,
STATUS VARCHAR2(10)
CHECK (status IN ('CREDIT', 'CASH')),
PROD_ID NUMBER
REFERENCES PRODUCTS(PRODUCT_ID),
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For which columns would an index be automatically created when you execute the above SQL statement? （）

A.SER_NO
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C.STATUS
D.PROD_ID
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The EMP table contains these columns:
LAST_NAME VARCHAR2 (25)
SALARY NUMBER (6,2)
DEPARTMENT_ID NUMBER (6)
You need to display the employees who have not been assigned to any department. You write the SELECT statement:
SELECT LAST_NAME, SALARY, DEPARTMENT_ID
FROM EMP
WHERE DEPARTMENT_ID = NULL;
What is true about this SQL statement ?（）

A.The SQL statement displays the desired results.
B.The column in the WHERE clause should be changed to display the desired results.
C.The operator in the WHERE clause should be changed to display the desired results.
D.The WHERE clause should be changed to use an outer join to display the desired results.

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In which three cases would you use the USING clause?（）

A.You want to create a nonequijoin.
B.The tables to be joined have multiple NULL columns.
C.The tables to be joined have columns of the same name and different data types.
D.The tables to be joined have columns with the same name and compatible data types.
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Which two tasks can you perform using only the TO_CHAR function? （）

A.convert 10 to 'TEN'
B.convert '10' to 10
C.convert 10 to '10'
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单项选择题

Examine the structure of the EMPLOYEES table:
EMPLOYEE_ID NUMBER Primary Key
FIRST_NAME VARCHAR2(25)
LAST_NAME VARCHAR2(25)
HIRE_DATE DATE
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CREATE table new_emp ( employee_id NUMBER, name VARCHAR2(30)); INSERT INTO new_emp SELECT employee_id , last_name from employees;
Savepoint s1;
UPDATE new_emp set name = UPPER(name);
Savepoint s2;
Delete from new_emp;
Rollback to s2;
Delete from new_emp where employee_id =180;
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Rollback to s2;
UPDATE new_emp set name = 'James' WHERE employee_id =180;
Rollback;
At the end of this transaction, what is true?（）

A.You have no rows in the table.
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D.Your last update fails to update any rows because employee ID 180 was already deleted.

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