What does the TRUNCATE statement do?（）……

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;

单项选择题Which statement correctly describes SQL and SQL*Plus?（）

A. Both SQL and /SQL*plus allow manipulation of values in the database.
B. /SQL* Plus recognizes SQL satement and sends them to the server; SQL is the Oracle proprietary interface for executing SQL statements.
C. /SQL* Plus language for communicating with the Oracle server to access data; SQL recognizes SQL statements and sends them to the server.
D. /SQL manipulates data and table definition in the database; /SQL* Plus does not allow manipulation of values in the database.

多项选择题Which two are true about aggregate functions? （）

A. You can use aggregate functions in any clause of a SELECT statement.
B. You can use aggregate functions only in the column list of the select clause and in the WHERE clause of a SELECT statement.
C. You can mix single row columns with aggregate functions in the column list of a SELECT statement by grouping on the single row columns.
D. You can pass column names, expressions, constants, or functions as parameter to an aggregate function.
E. You can use aggregate functions on a table, only by grouping the whole table as one single group.
F. You cannot group the rows of a table by more than one column while using aggregate functions.