單項選擇題

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';

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單項選擇題

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;

單項選擇題

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.

Examine the description of the EMPLOYEES table: Which statement produces the number of different departments that have employees with last name Smith?（）

你可能感興趣的試題

Which SELECT statement should you use to extract the year from the system date and display it in the format "1998"?（）

In which scenario would an index be most useful?（）

Examine the description of the EMPLOYEES table:

Which statement produces the number of different departments that have employees with last name Smith?（）