多项选择题
Examine the description of the MARKS table:
STD_ID NUMBER(4)
STUDENT_NAME VARCHAR2(30)
SUBJ1 NUMBER(3)
SUBJ2 NUMBER(3)
SUBJ3 NUMBER(3)
SUBJ1, SUBJ2, and SUBJ3 indicate the marks (grades) obtained by a student in the three subjects. Which two statements are valid? （）
A.SELECT SUM(subj1, subj2, subj3) FROM marks;
B.SELECT SUM(subj1 + subj2 + subj3) FROM marks;
C.SELECT SUM(subj1), SUM(subj2), SUM(subj3) FROM marks;
D.SELECT MAX(subj1, subj2, subj3) FROM marks;
E.SELECT MINIMUM(subj1) FROM marks;
F.SELECT COUNT(std_id) FROM marks WHERE subj1 >= AVG(subj1);
相关考题
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单项选择题
Examine the description of the EMPLOYEES table: 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'; -
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
In which scenario would an index be most useful?（）
A.The indexed column is declared as NOT NULL.
B.The indexed columns are used in the FROM clause.
C.The indexed columns are part of an expression.
D.The indexed column contains a wide range of values.
