1Z0-007章節(jié)練習(2019.12.14)

Examine the structure of the EMPLOYEES table:
Column name Data type Remarks
EMPLOYEE_ID NUMBER NOT NULL, Primary Key
LAST_NAME VARCNAR2(30)
FIRST_NAME VARCNAR2(30)
JOB_ID NUMBER
SAL NUMBER
MGR_ID NUMBER References EMPLOYEE_ID column
DEPARTMENT_ID NUMBER
You need to create an index called NAME_IDX on the first name and last name fields of the EMPLOYEES table. Which SQL statement would you use to perform this task?（）

The EMPLOYEES table has these columns:
LAST NAME VARCHAR2(35)
SALARY NUMBER(8,2)
HIRE_DATE DATE
Management wants to add a default value to the SALARY column. You plan to alter the table by using this SQL statement:
ALTER TABLE EMPLOYEES
MODIFY ( SALARY DEFAULT 5000);
What is true about your ALTER statement?（）

You need to design a student registration database that contains several tables storing academic information.
The STUDENTS table stores information about a student. The STUDENT_GRADES table stores
information about the student's grades. Both of the tables have a column named STUDENT_ID. The STUDENT_ID column in the STUDENTS table is a primary key.
You need to create a foreign key on the STUDENT_ID column of the STUDENT_GRADES table that
points to the STUDENT_ID column of the STUDENTS table. Which statement creates the foreign key?（）