問題文
A nightly process writes order rows into a data extension using the customer number as the primary key. What does declaring that primary key change about how the table accepts writes?
選択肢
- A write that carries an existing customer number updates the matching row instead of adding a second row that repeats the same customer number.
- A write that carries a null customer number is accepted and the platform generates a substitute value so the row can be stored anyway.
- A write that carries a new customer number is rejected until an administrator adds that value to the list of keys the table already accepts.
- A write that carries an existing customer number keeps the earlier row and adds a second row that records the newer version of the same order.