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.
- C
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