Which two statements complete a transaction? （）

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. &&

单项选择题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.

单项选择题Which constraint can be defines only at the column level? （）

A. UNIQUE
B. NOT NULL
C. CHECK
D. PRIMARY KEY
E. FOREIGN KEY