Examine these commands which execute successfully: mYsql> CREATE TABLE income (acct_num INT, amount DECIMAL(10,2)); mysql> CREATE TRIGGER subtotal BEFORE INSERT ON income FOR EACH ROW SET @subtotal…

Question

Options

• AThe trigger activates after any row has been inserted into the table.
• BThe trigger body set causes trigger activation.
• CThe trigger activates after any row in the table has been updated.
• DExecution of an insert statement causes the trigger to activate.

• A
  2% (1)
• B
  7% (3)
• C
  13% (6)
• D
  78% (35)

Explanation

Option D is correct because the trigger is defined with BEFORE INSERT ON income, meaning any time an INSERT statement is executed against the income table, the trigger activates - specifically just before the row is written.

Why the distractors are wrong:

• A is wrong because the timing keyword is BEFORE, not AFTER - the trigger fires before the insert completes, not after.
• B confuses cause and effect: the SET statement is the trigger body (what runs when triggered), not the mechanism that causes activation; the INSERT event causes activation.
• C is wrong on two counts - the event is INSERT, not UPDATE, and the timing is BEFORE, not AFTER.

Memory tip: Read the trigger definition left to right - BEFORE INSERT ON income tells you when (before), what event (insert), and on which table (income). The event keyword (INSERT, UPDATE, or DELETE) always determines what SQL operation activates the trigger.

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