多项选择题

Which two statements complete a transaction? （）

A. DELETE employees;
B. DESCRIBE employees;
C. ROLLBACK TO SAVE POINT C;
D. GRANT SELECT ON employees TO SCOTH
E. ALTER TABLE employees SET UNUSED COLUMN sal;
F. Select MAX(sal) FROM employees WHERE department _ id 20;

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单项选择题

The DBA issues this SQL command:
CREATE USER scott
IDENTIFIES by tiger;
What privileges does the user Scott have at this point? （）

A. No privileges.
B. Only the SELECT privilege.
C. Only the CONNECT privilege.
D. All the privileges of a default user.

单项选择题

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?（）

A. Column definitions cannot be altered to add DEFAULT values.
B. A change to the DEFAULT value affects only subsequent insertions to the table.
C. Column definitions cannot be altered at add DEFAULT values for columns with a NUMBER data type.
D. All the rows that have a NULL value for the SALARY column will be updated with the value 5000.

单项选择题

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. &&