单项选择题

Which statement creates a new user?（）

A. CREATE USER susan;
B. CREATE OR REPLACE USER susan;
C. CREATE NEW USER susan    DEFAULT;
D. CREATE USER susan    IDENTIFIED BY blue;
E. CREATE NEW USER susan   IDENTIFIED by blue;
F. CREATE OR REPLACE USER susan   IDENTIFIED BY blue;

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单项选择题You need to change the definition of an existing table. The COMMERCIALS table needs its DESCRIPTION column changed to hold varying length characters up to 2000 bytes. The column can currently hold 1000 bytes per value. The table contains 20000 rows. Which statement is valid?（）

A. ALTER TABLE commercials   MODIFY (description CHAR2(2000));
B. ALTER TABLE commercials   CHANGE (description CHAR2(2000));
C. ALTER TABLE commercials   CHANGE (description VARCHAR2(2000));
D. ALTER TABLE commercials   MODIFY (description VARCHAR2(2000));
E. You cannot increase the size of a column if the table has rows.

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

单项选择题Which is an SQL*Plus command?（）

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

单项选择题Examine the structure of the STUDENTS table: STUDENT_ID NUMBER NOT NULL, Primary Key STUDENT_NAME VARCHAR2(30) COURSE_ID VARCHAR2(10) NOT NULL MARKS NUMBER START_DATE DATE FINISH_DATE DATE You need to create a report of the 10 students who achieved the highest ranking in the course INT SQL and who completed the course in the year 1999. Which SQL statement accomplishes this task?（）

A. SELECT student_ id, marks, ROWNUM "Rank" FROM students WHERE ROWNUM <= 10 AND finish_date BETWEEN '01-JAN-99' AND '31-DEC-99 AND course_id = 'INT_SQL' ORDER BY mark DESC;
B. SELECT student_id, marks, ROWID "Rank" FROM students WHERE ROWID <= 10 AND finish_date BETWEEN '01-JAN-99' AND '31-DEC-99' AND course_id = 'INT_SQL' ORDER BY mark;
C. SELECT student_id, marks, ROWNUM "Rank" FROM (SELECT student_id, marks FROM students WHERE ROWNUM <= 10 AND finish_date BETWEEN '01-JAN-99' AND '31-DEC- 99' AND course_id = 'INT_SQL' ORDER BY mark DESC;
D. SELECT student_id, marks, ROWNUM "Rank" FROM (SELECT student_id, marks FROM students WHERE (finish_date BETWEEN '01-JAN-99 AND '31-DEC-99' AND course_id = 'INT_SQL' ORDER BY marks DESC) WHERE ROWNUM <= 10;
E. SELECT student id, marks, ROWNUM "Rank" FROM (SELECT student_id, marks FROM students ORDER BY marks) WHERE ROWNUM <= 10 AND finish date BETWEEN '01-JAN-99' AND '31-DEC-99' AND course _ id 'INT_SQL';

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;