Management has asked you to calculate the value 12*salary*commission_pct for all the employees in the EMP table. The EMP table contains these columns: LAST NAME VARCHAR2(35) NOT NULL SALARY NUMBER(9,2) NOT NULL COMMISSION_PCT NUMBER(4,2) Which statement ensures that a value is displayed in the calculated column for all employees?

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  1. SELECT last_name, 12*salary*commission_pct FROM emp;

  2. SELECT last_name, 12*salary* (commission_pct,0) FROM emp;

  3. SELECT last_name, 12*salary*(nvl(commission_pct,0)) FROM emp

  4. SELECT last_name, 12*salary*(decode(commission_pct,0)) FROM emp;

Show answer
Correct Option: C

AI Explanation

To ensure that a value is displayed in the calculated column for all employees, you need to handle the case when the commission_pct is null. The NVL function can be used to replace null values with a default value.

Let's go through each option to understand why it is correct or incorrect:

Option A) SELECT last_name, 12*salary*commission_pct FROM emp; This option is incorrect because it does not handle the case when commission_pct is null. If commission_pct is null for any employee, the result of the calculation will also be null for that employee.

Option B) SELECT last_name, 12*salary* (commission_pct,0) FROM emp; This option is incorrect because it uses an invalid syntax. The expression (commission_pct,0) is not a valid way to handle null values.

Option C) SELECT last_name, 12*salary*(nvl(commission_pct,0)) FROM emp This option is correct because it uses the NVL function to replace null values with 0. If commission_pct is null for any employee, the NVL(commission_pct,0) expression will evaluate to 0, and the calculation will still produce a value.

Option D) SELECT last_name, 12*salary*(decode(commission_pct,0)) FROM emp; This option is incorrect because the DECODE function is used incorrectly. The DECODE function should have a default value as the last argument, but in this case, it is missing. Additionally, the DECODE function is not necessary to handle null values.

The correct answer is C. This option ensures that a value is displayed in the calculated column for all employees by using the NVL function to replace null values with 0.

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