You added a PHONE_NUMBER column of NUM...

单项选择题 You added a PHONE_NUMBER column of NUMBER data type to an existing EMPLOYEES table. The EMPLOYEES table already contains records of 100 employees. Now, you want to enter the phone numbers of each of the 100 employees into the table. Some of the employees may not have a phone number available.
Which data manipulation operation do you perform?（）

A. MERGE
B. INSERT
C. UPDATE
D. ADD
E. ENTER
F. You cannot enter the phone numbers for the existing employee records.

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1.单项选择题What does the TRUNCATE statement do?（）

A. Removes the table
B. Removes all rows from a table
C. Shortens the table to 10 rows
D. Removes all columns from a table
E. Removes foreign keys from a table

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2.单项选择题Which is an /SQL*Plus command?（）

A. INSERT
B. UPDATE
C. SELECT
D. DESCRIBE
E. DELETE
F. RENAME

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3.单项选择题 Examine the data of the EMPLOYEES table.
EMPLOYEES (EMPLOYEE_ID is the primary key. MGR_ID is the ID of managers and refers to the EMPLOYEE_ID)

Evaluate this SQL statement:

What is its output?（）

A.
B.
C.
D.
E. The SQL statement produces an error.

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4.单项选择题Which SELECT statement should you use to extract the year from the system date and display it in the format "1998"?（）

A. SELECT TO_CHAR(SYSDATE,'yyyy') FROM dual;
B. SELECT TO_DATE(SYSDATE,'yyyy') FROM dual;
C. SELECT DECODE(SUBSTR(SYSDATE, 8), 'YYYY') FROM dual;
D. SELECT DECODE(SUBSTR(SYSDATE, 8), 'year') FROM dual;
E. SELECT TO_CHAR(SUBSTR(SYSDATE, 8,2),'yyyy') FROM dual;

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5.单项选择题 The EMPLOYEES table contains these columns:
LAST_NAME VARCHAR2 (25)
SALARY NUMBER (6,2)
COMMISSION_PCT NUMBER (6)
You need to write a query that will produce these results:
1. Display the salary multiplied by the commission_pct.
2. Exclude employees with a zero commission_pct.
3. Display a zero for employees with a null commission value.
Evaluate the SQL statement:
SELECT LAST_NAME, SALARY*COMMISSION_PCT
FROM EMPLOYEES
WHERE COMMISSION_PCT IS NOT NULL;
What does the statement provide?（）

A.All of the desired results
B.Two of the desired results
C.One of the desired results
D.An error statement

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6.单项选择题A subquery can be used to （）.

A. Create groups of data
B. Sort data in a specific order
C. Convert data to a different format
D. Retrieve data based on an unknown condition

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7.单项选择题Which clause should you use to exclude group results?（）

A. WHERE
B. HAVING
C. RESTRICT
D. GROUP BY
E. ORDER BY

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8.单项选择题 Scott issues the SQL statements:
CREATE TABLE dept
(deptno NUMBER(2),
dname VARCHAR2(14),
loc VARCHAR2(13)};
GRANT SELECT
ON DEPT
T0 SUE;
If Sue needs to select from Scott's DEPT table, which command should she use?（）

A.SELECT*FROMDEPT；
B.SELECT*FROMSCOTT.DEPT；
C.SELECT*FROMDBASCOTTDEPT；
D.SELECT*FROMALL_USERSWHEREUSER_NAME='；SCOTT'；ANDTABLENAME='；DEPT'；；

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9.单项选择题What is true about joining tables through an equijoin?（）

A. You can join a maximum of two tables through an equijoin.
B. You can join a maximum of two columns through an equijoin.
C. You specify an equijoin condition in the SELECT or FROM clauses of a SELECT statement.
D. To join two tables through an equijoin, the columns in the join condition must be primary key and foreign key columns.
E. You can join n tables (all having single column primary keys) in a SQL statement by specifying a minimum of n-1 join conditions.

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10.多项选择题Which two statements about subqueries are true?（）

A. A single row subquery can retrieve data from only one table.
B. A SQL query statement cannot display data from table B that is referred to in its subquery, unless table B is included in the main query's FROM clause.
C. A SQL query statement can display data from table B that is referred to in its subquery, without including table B in its own FROM clause.
D. A single row subquery can retrieve data from more than one table.
E. A single row subquery cannot be used in a condition where the LIKE operator is used for comparison.
F. A multiple-row subquery cannot be used in a condition where the LIKE operator is used for comparison.

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