In Oracle oriented database exams, what is often cited as the maximum number of distinct triggers that can be defined on a single table when you consider different combinations of timing and events such as before and after for insert, update, and delete operations?

Difficulty: Medium

Correct Answer: 12

Explanation:


Introduction / Context:
Database triggers are procedural code blocks that fire automatically in response to events on a table or view. In Oracle related certification questions, candidates are often asked about the theoretical number of possible triggers associated with a single table, based on combinations of timing and events. While modern Oracle versions allow more flexibility, exam style questions frequently refer to a classic breakdown of triggers by before or after timing and by insert, update, and delete operations.


Given Data / Assumptions:

  • The context is Oracle oriented certification style content.
  • Triggers are defined for table level events such as insert, update, and delete.
  • Each event can have before and after timing variants.
  • Row level and statement level triggers are considered separately.
  • The question asks for a maximum count used in common exam explanations.


Concept / Approach:
Classically, exam explanations break down the triggers per table as follows. For each of the three DML operations insert, update, and delete, you can have a before statement trigger and an after statement trigger, as well as a before row trigger and an after row trigger. That yields four triggers per operation. With three operations, there are twelve possible distinct triggers when you multiply the number of operations by the number of timing and level combinations. This count is often emphasised in exam material, even though practical implementations can be more flexible and are not strictly limited to this number.


Step-by-Step Solution:
Step 1: List the DML operations that can fire triggers on a table: insert, update, and delete. Step 2: For each operation, identify before and after timing options, giving two timing points. Step 3: For each timing point, recognise that you can define both statement level and row level triggers. Step 4: Multiply the combinations: 3 operations times 2 timings times 2 levels equals 12 potential triggers. Step 5: Select the option that matches this commonly cited number, which is 12.


Verification / Alternative check:
By constructing a small table and writing out trigger definitions for before insert, before update, before delete, and after versions of each at both statement and row levels, you would see that 12 distinct definitions are possible under the classic model. Exam guides often explicitly display a matrix showing three operations, two timings, and two levels to justify the figure of 12 triggers.


Why Other Options Are Wrong:
Options A, B, C, and D list values 4, 6, 8, and 10, which do not correctly account for all combinations of insert, update, delete, before, after, row level, and statement level triggers commonly discussed in exam material. They either forget one of the operations, overlook one of the timing options, or ignore one of the levels. The value 12 most closely matches the traditional breakdown used in Oracle certification style questions.


Common Pitfalls:
A frequent source of confusion is thinking only about row level triggers or only about before triggers and forgetting after or statement level variants. Another pitfall is assuming that the number represents a hard technical limit in the database engine rather than a conceptual explanation of distinct trigger types. For exam purposes, focus on the theoretical combinations of timing and level for each DML operation, which leads to the number twelve.


Final Answer:
In Oracle certification style questions, the often cited maximum number of distinct triggers on a single table is 12, based on combinations of timing and event type.

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