单项选择题
A. The DESCRIBE DEPT statement displays the structure of the DEPT table.
B. The ROLLBACK statement frees the storage space occupies by the DEPT table.
C. The DESCRIBE DEPT statement returns an error ORA-04043: object DEPT does not exist.
D. The DESCRIBE DEPT statement displays the structure of the DEPT table only if there is a COMMIT statement introduced before the ROLLBACK statement.
单项选择题 Which SQL statement defines the FOREIGN KEY constraint on the DEPTNO column of the EMP table?（）
单项选择题 You need to modify the STUDENTS table to add a primary key on the STUDENT_ID column. The table is currently empty.Which statement accomplishes this task?（）
多项选择题 Which three are DATETIME data types that can be used when specifying column definitions? （）