164.Examine the command that is used to create a table: SQL> CREATE TABLE orders( oid NUMBER(6) PRI

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.
答案：BD
解析：主键=unique+not null，因此会创建唯一索引，并且索引和表如果没有指定的话，他们在一个表空间中
--创建表，并指定表空间
SQL> create table wwwa(id integer primary key) tablespace TEST;
Table created.
--查看索引所在的表空间
SQL> select tablespace_name from user_indexes where table_owner='SKD';
TABLESPACE_NAME
------------------------------
TEST
--查看用户默认表空间
SQL> conn / as sysdba
Connected.
SQL> select default_tablespace from dba_users where username='SKD';
DEFAULT_TABLESPACE
------------------------------
USER2
C这里没有关系，user表空间中是否存在其他对象题目中没有说明