多項(xiàng)選擇題

In which three cases would you use the USING clause?（）

A.You want to create a nonequijoin.
B.The tables to be joined have multiple NULL columns.
C.The tables to be joined have columns of the same name and different data types.
D.The tables to be joined have columns with the same name and compatible data types.
E.You want to use a NATURAL join, but you want to restrict the number of columns in the join condition.

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多項(xiàng)選擇題

Which two tasks can you perform using only the TO_CHAR function? （）

A.convert 10 to 'TEN'
B.convert '10' to 10
C.convert 10 to '10'
D.convert 'TEN' to 10
E.convert a date to a character expression
F.convert a character expression to a date

單項(xiàng)選擇題

Examine the structure of the EMPLOYEES table:
EMPLOYEE_ID NUMBER Primary Key
FIRST_NAME VARCHAR2(25)
LAST_NAME VARCHAR2(25)
HIRE_DATE DATE
You issue these statements:
CREATE table new_emp ( employee_id NUMBER, name VARCHAR2(30)); INSERT INTO new_emp SELECT employee_id , last_name from employees;
Savepoint s1;
UPDATE new_emp set name = UPPER(name);
Savepoint s2;
Delete from new_emp;
Rollback to s2;
Delete from new_emp where employee_id =180;
UPDATE new_emp set name = 'James';
Rollback to s2;
UPDATE new_emp set name = 'James' WHERE employee_id =180;
Rollback;
At the end of this transaction, what is true?（）

A.You have no rows in the table.
B.You have an employee with the name of James.
C.You cannot roll back to the same savepoint more than once.
D.Your last update fails to update any rows because employee ID 180 was already deleted.