OCP 1Z0 052 164

164. Examine the command that is used to create a table:

SQL> CREATE TABLE orders(oid NUMBER(6) PRIMARY KEY, odate DATE, ccode NUMBER

(6), oamt NUMBER(10,2)) TABLESPACE users;

Which two statements are true about the effect of the above command? (Choose two.)

A.A CHECK constraint is created on the OID column.

B.A NOT NULL constraint is created on the OID column.

C.The ORDERS table is the only object created in the USERS tablespace.

D.The ORDERS table and a unique index are created in the USERS tablespace.

E.The ORDERS table is created in the USERS tablespace and a unique index is created on the OID

column in the SYSTEM tablespace.

Answer: BD

主键包含两个要素，1 非空 2 唯一，唯一功能依赖于索引

SQL> CREATE TABLE orders(oid NUMBER(6) PRIMARY KEY, odate DATE, ccode NUMBER
2  (6), oamt NUMBER(10,2)) TABLESPACE users;

Table created.

SQL> select index_name from user_indexes where table_name = upper('orders');

INDEX_NAME
------------------------------
SYS_C0014469

SQL> desc orders;
Name                                      Null?    Type
----------------------------------------- -------- ----------------------------
OID                                       NOT NULL NUMBER(6)
ODATE                                              DATE
CCODE                                              NUMBER(6)
OAMT                                               NUMBER(10,2)