试题详情
- 单项选择题 Click the Exhibit button and examine the data in the EMPLOYEES table. On the EMPLOYEES table, EMPLOYEE_ID is the primary key. MGR_ID is the ID of managers and refers to the EMPLOYEE_ID. The JOB_ID column is a NOT NULL column. Evaluate this DELETE statement: DELETE employee_id, salary, job_id FROM employees WHERE dept_id = 90; Why does the DELETE statement fail when you execute it?（）
A、There is no row with dept_id 90 in the EMPLOYEES table.
B、You cannot delete the JOB_ID column because it is a NOT NULL column.
C、You cannot specify column names in the DELETE clause of the DELETE statement.
D、You cannot delete the EMPLOYEE_ID column because it is the primary key of the table.
关注下方微信公众号，在线模考后查看
热门试题
- You are the DBA for
- A SELECT statement
- The DBA issues this
- Which SQL statement
- The user Alice wants
- The STUDENT_GRADES
- Which four statement
- What is true regardi
- ClicktheExhibitbutto
- Which four statement
- The user Alice wants
- In which case would
- The database adminis
- Examine the structu
- Examinethestructureo
- Examine the structu
- Which SQL statement
- Evaluate this SQL s
- The EMPLOYEES table
- Which view should a