013[Oracle题目]EMPLOYEES表结构如下:
EMPLOYEE_ID NUMBER NOT NULL,PRIMARY KEY
LAST_NAME VARCHAR(30)
FIRST_NAME VARCHAR(20)
JOB_ID NUMBER
SAL NUMBER
MGR_ID字段的数据类型为NUNBER,参照EMPLYEE_ID列和DEPARTMENT_ID列(NUMBER)
现需要在FIRST_NAME和LAST_NAME字段上建立名为NAME_INDEX的索引,下面哪个SQL语句能执行这项任务?(选择1项)
A)CREATE INDEX NAME_INDEX(first_name,last_name);
B)CREATE IDNEX NAME_INDEX(first_name AND last_name);
C)CREATE INDEX NAME_IDNEX ON employees (first_name,last_name);
D)CREAT INDEX NAME_INDEX FOR employees (first_name,last_name);