Answers to practice exam questionsA2: Answer: D. The other definitions are incorrect. REAL data consists of single-precision floating-point numbers, which can be less than, equal to, or greater than 21. DOUBLE data consists of double-precision floating-point numbers. SMALLINT data consists of small integers, but they need not be less than 22.
A3: Answer: B and D. The statements in the other options are false. Option A is false because no user-defined settings control how DB2 treats null values. Option C is false because a null value is not equivalent to a blank. Option E is false because a null value is not equivalent to a zero value.
A4: Answer: A. The statements in the other options are true. Option A is false because using an index might improve performance, but in some cases a scan of the entire table actually results in better performance than when an index is used.