单项选择题

Examine the structure of the EMPLOYEES and NEW_EMPLOYEE……

Examine the structure of the EMPLOYEES and NEW_EMPLOYEES tables:
EMPLOYEES
EMPLOYEE_ID NUMBER Primary Key
FIRST_NAME VARCHAR2(25)
LAST_NAME VARCHAR2(25)
HIRE_DATE DATE
NEW_EMPLOYEES
EMPLOYEE_ID NUMBER Primary Key
NAME VARCHAR2 (60)
Which DELETE statement is valid?（）

A. DELETE FROM employees WHERE employee_id = (SELECT employee_id FROM employees);
B. DELETE * FROM employees WHERE employee_id = (SELECT employee_id FROM new_ employees);
C. DELETE FROM employees WHERE employee_id IN (SELECT employee_id FROM new_employees WHERE name = 'carrey');
D. DELETE * FROM employees WHERE employee_id IN (SELECT employee_id FROM new_employees WHERE name = 'carrey');

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多项选择题Evaluate this SQL statement: SELECT e.emp_name, d.dept_name FROM employees e JOIN departments d USING (department_id) WHERE d.department_id NOT IN (10,40) ORSER BY dept_name; The statement fails when executed. Which change fixes the error?（）

A. remove the ORDER BY clause
B. remove the table alias prefix from the WHERE clause
C. remove the table alias from the SELECT clause
D. prefix the column in the USING clause with the table alias
E. prefix the column in the ORDER BY clause with the table alias
F. replace the condition "d.department_id NOT IN (10,40)" in the WHERE clause with "d.department_id <> 10 AND d.department_id <> 40"

多项选择题Which three statements about subqueries are true? （）

A. A main query can have more than one subquery.
B. A subquery can have more than one main query.
C. The subquery and main query must retrieve data from the same table.
D. The subquery and main query can retrieve data from different tables.
E. Only one column or expression can be compared between the subquery and main query.
F. Multiple columns or expression can be compared between the subquery and main query.

单项选择题EXHIBIT, Emp Table Exhibit A Exhibit B Examine the data from the EMP table. Evaluate this SQL statement: SELECT * FROM emp WHERE emp _ id = 3); WHERE commission = (SELECT commission FROM emp What is the result when the query is executed?（）

A. Exhibit A
B. Exhibit B
C. The query returns no rows
D. The query fails because the outer query is retrieving more than one column
E. The query fails because both the inner and outer queries are retrieving data from the same table.

多项选择题Which two statements about creating constraints are true?（）

A. Constraint names must start with SYS_C
B. All constraints must be defines at the column level
C. Constraints can be created after the table is created
D. Constraints can be created at the same time the table is created
E. Information about constraints is found in the VIEW_CONSTRAINTS dictionary view

单项选择题For which action can you use the TO_DATE function?（）

A. Convert any date literal to a date
B. Convert any numeric literal to a date
C. Convert any character literal to a date
D. Convert any date to a character literal
E. Format '10-JAN-99' to 'January 10 1999'