单选题“雇员”表包含以下列： EMPLOYEE_ID NOT NULL, Primary Key SSNUM NOT NULL, Unique LAST_NAME VARCHAR2(25) FIRST_NAME VARCHAR2(25) DEPARTMENT_ID NUMBER 部门表中 DEPARTMENT_ID 列的外键 SALARY NUMBER(8,2) 如果执行以下语句： CREATE INDEX emp_name_idx ON employees(last_name, first_name); 以下哪个说法是的（）A此语句会创建一个基于函数的索引B因为语法错误，此语句将失败C该语句将创建一个组合唯一索引D该语句将创建一个组合非唯一索引
单选题
“雇员”表包含以下列： EMPLOYEE_ID NOT NULL, Primary Key SSNUM NOT NULL, Unique LAST_NAME VARCHAR2(25) FIRST_NAME VARCHAR2(25) DEPARTMENT_ID NUMBER 部门表中 DEPARTMENT_ID 列的外键 SALARY NUMBER(8,2) 如果执行以下语句： CREATE INDEX emp_name_idx ON employees(last_name, first_name); 以下哪个说法是的（）
A
此语句会创建一个基于函数的索引
B
因为语法错误，此语句将失败
C
该语句将创建一个组合唯一索引
D
该语句将创建一个组合非唯一索引
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