123. View the Exhibit and examine the structure of the ORDERS and ORDER_ITEMS

tables.In the ORDERS table, ORDER_ID is the PRIMARY KEY and ORDER_DATE has

the DEFAULT value as SYSDATE.Evaluate the following statement:

UPDATE orders SET order_date=DEFAULT

WHERE order_id IN (SELECT order_id FROM order_items WHERE qty IS NULL);

What would be the outcome of the above statement?

A. The UPDATE statement would not work because the main query and the subquery

use different tables.

B. The UPDATE statement would not work because the DEFAULT value can be used

only in INSERT statements.

C. The UPDATE statement would change all ORDER_DATE values to SYSDATE

provided the current ORDER_DATE is NOT NULL and QTY is NULL.

D. The UPDATE statement would change all the ORDER_DATE values to SYSDATE

irrespective of what the current ORDER_DATE value is for all orders where

QTY is NULL.

Answer: D

Irrespective:不考虑

SQL> create table tt(a date default sysdate);

SQL> insert into tt values(sysdate);

SQL> insert into tt values(to_date('2004-05-07 13:23:44','yyyy-mm-dd

hh24:mi:ss'));

SQL> update tt set a=default;

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