Which two statements about sequences are true? (Choose two.) A. You use a NEXTVAL pseudo column to look at the next possible value that would be generated from a sequence, without actually retrieving the value. B. You use a CURRVAL pseudo column to look at the current value just generated from a sequence, without affecting the further values to be generated from the sequence. C. You use a NEXTVAL pseudo column to obtain the next possible value from a sequence by actually retrieving the value from the sequence. D. You use a CURRVAL pseudo column to generate a value from a sequence that would be used for a specified database column. E. If a sequence starting from a value 100 and incremented by 1 is used by more than one application, then all of these applications could have a value of 105 assigned to their column whose value is being generated by the sequence. F. You use a REUSE clause when creating a sequence to restart the sequence once it generates the maximum value defined for the sequence.

technology databases

  1. A

  2. B

  3. C

  4. D

  5. E

  6. F

Show answer
Correct Option: B,C

AI Explanation

To answer this question, let's go through each option to understand why it is correct or incorrect:

Option A) You use a NEXTVAL pseudo column to look at the next possible value that would be generated from a sequence, without actually retrieving the value. - This option is incorrect. The NEXTVAL pseudo column is used to retrieve the next value from a sequence, not just to look at it without retrieving it.

Option B) You use a CURRVAL pseudo column to look at the current value just generated from a sequence, without affecting the further values to be generated from the sequence. - This option is correct. The CURRVAL pseudo column is used to retrieve the current value generated from a sequence without affecting the sequence itself.

Option C) You use a NEXTVAL pseudo column to obtain the next possible value from a sequence by actually retrieving the value from the sequence. - This option is correct. The NEXTVAL pseudo column is used to retrieve the next value from a sequence by actually retrieving it from the sequence.

Option D) You use a CURRVAL pseudo column to generate a value from a sequence that would be used for a specified database column. - This option is incorrect. The CURRVAL pseudo column is used to retrieve the current value generated from a sequence, not to generate a new value.

Option E) If a sequence starting from a value 100 and incremented by 1 is used by more than one application, then all of these applications could have a value of 105 assigned to their column whose value is being generated by the sequence. - This option is incorrect. Each application will retrieve the next value from the sequence independently, so they will receive different values. In this case, each application will receive a different value after 100.

Option F) You use a REUSE clause when creating a sequence to restart the sequence once it generates the maximum value defined for the sequence. - This option is incorrect. The REUSE clause is not used to restart the sequence once it reaches the maximum value. It is used when dropping and recreating a sequence to reuse the existing values.

The correct answers are B) You use a CURRVAL pseudo column to look at the current value just generated from a sequence, without affecting the further values to be generated from the sequence. and C) You use a NEXTVAL pseudo column to obtain the next possible value from a sequence by actually retrieving the value from the sequence.

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