OCP题库：1Z0-051-001题
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View the Exhibit and examine the structure of the SALES, CUSTOMERS, PRODUCTS, and TIMES
tables.
The PROD_ID column is the foreign key in the SALES table, which references the PRODUCTS table.
Similarly, the CUST_ID and TIME_ID columns are also foreign keys in the SALES table referencing the
CUSTOMERS and TIMES tables, respectively.
Evaluate the following CREATE TABLE command:
CREATE TABLE new_sales(prod_id, cust_id, order_date DEFAULT SYSDATE)
AS
SELECT prod_id, cust_id, time_id
FROM sales;
Which statement is true regarding the above command?
A. The NEW_SALES table would not get created because the DEFAULT value cannot be specified in the
column definition.
B. The NEW_SALES table would get created and all the NOT NULL constraints defined on the specified
columns would be passed to the new table.
C. The NEW_SALES table would not get created because the column names in the CREATE TABLE
command and the SELECT clause do not match.
D. The NEW_SALES table would get created and all the FOREIGN KEY constraints defined on the
specified columns would be passed to the new table.
Answer: B
试题解析：
A答案：默认sysdate可以在列出被指定。
sh@TEST0924> CREATE TABLE new_sales(prod_id, cust_id, order_date DEFAULT SYSDATE) AS
2 SELECT prod_id, cust_id, time_id FROM sales;
Table created.
B答案：NULL约束会传递。由以下可以看出，not null是可以传递的。B正确
C答案：
由A中所见，此表是可以创建的，虽然字段名不一样，但数据库类型一样，就可以创建表。C错误。
D答案：
由B第二种方法看出，仅仅只是传递了not null约束，而SALES_PRODUCT_FK，SALES_CUSTOMER_FK，SALES_TIME_FK这三个外键约束是没有被传递的。
