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单项选择题

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 last_ name = ('Carrey')'

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单项选择题The CUSTOMERS table has these columns: CUSTOMER_ID NUMBER (4) NOT NULL CUSTOMER_NAME VARCHAR2 (100) NOT NULL STREET_ADDRESS VARCHAR2 (150) CITY_ADDRESS VARHCAR2 (50) STATE_ADDRESS VARCHAR2 (50) PROVINCE_ADDRESS VARCHAR2 (50) COUNTRY_ADDRESS VARCHAR2 (50) POSTAL_CODE VARCHAR2 (12) CUSTOMER_PHONE VARCHAR2 (20) The CUSTOMER_ID column is the primary key for the table. You need to determine how dispersed your customer base is. Which expression finds the number of different countries represented in the CUSTOMERS table?（）

A. COUNT(UPPER(country_address))
B. COUNT(DIFF(UPPER(country_address)))
C. COUNT(UNIQUE(UPPER(country_address)))
D. COUNT DISTINTC UPPER(country_address)
E. COUNT(DISTINTC (UPPER(country_address)))

单项选择题Evaluate the SQL statement: SELECT ROUND(45.953, -1), TRUNC(45.936, 2) FROM dual; Which values are displayed? （）

A. 46 and 45
B. 46 and 45.93
C. 50 and 45.93
D. 50 and 45.9
E. 45 and 45.93
F. 45.95 and 45.93

单项选择题Which SQL statement accepts user input for the columns to be displayed, the table name, and WHERE condition? （）

A. SELECT &1, "&2" FROM &3 WHERE last_name = '&8';
B. SELECT &1, '&2' FROM &3 WHERE '& last_name = '&8';
C. SELECT &1, &2 FROM &3 WHERE last_name = '&8';
D. SELECT &1, '&2' FROM EMP WHERE last_name = '&8';

多项选择题Which two statements are true about WHERE and HAVING clauses? （）

A. A WHERE clause can be used to restrict both rows and groups.
B. A WHERE clause can be used to restrict rows only.
C. A HAVING clause can be used to restrict both rows and groups.
D. A HAVING clause can be used to restrict groups only.
E. A WHERE clause CANNOT be used in a query of the query uses a HAVING clause.
F. A HAVING clause CANNOT be used in subqueries.

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.