單項選擇題

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:

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.

你可能感興趣的試題

單項選擇題

Which substitution variable would you use if you want to reuse the variable without prompting the user each time?（）

A.&
B.ACCEPT
C.PROMPT
D.&&

單項選擇題

What is true about the WITH GRANT OPTION clause?（）

A.It allows a grantee DBA privileges.
B.It is required syntax for object privileges.
C.It allows privileges on specified columns of tables.
D.It is used to grant an object privilege on a foreign key column.
E.It allows the grantee to grant object privileges to other users and roles.

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: Why does the DELETE statement fail when you execute it?（）

你可能感興趣的試題

Which substitution variable would you use if you want to reuse the variable without prompting the user each time?（）

What is true about the WITH GRANT OPTION clause?（）

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:

Why does the DELETE statement fail when you execute it?（）