Given the following tables: CONTINENTS ID NAME COUNTRIE……

单项选择题Which of the following statements eliminates all but one of each set of duplicate rows in the DEPT column in the STAFF table?（）

A.SELECT UNIQUE dept FROM staff
B.SELECT DISTINCT dept FROM staff
C.SELECT (dept) UNIQUE FROM staff
D.SELECT (dept) DISTINCT FROM staff

单项选择题In which of the following situations should correlation names be used?（）

A.A table referenced in the FROM clause has no indexed column.
B.The table referenced in the FROM clause has more than 200 columns.
C.Two or more tables in the FROM clause have identical column names.
D.The FROM clause contains two or more tables in the SELECT statement.

单项选择题Consider the following table called EMPLOYEES: ID FIRSTNAME LASTNAME JOB LEVEL CLERK 3 If the following SQL statement is executed, how many rows will be deleted? DELETE FROM employees WHERE 1 = 1（）

A.0
B.1
C.3
D.6

单项选择题Which of the following is a feature of a unit of work?（）

A.It applies to a single data server.
B.It is a recoverable sequence of operations.
C.Its value can be queried from the system catalog tables.
D.It begins when the application connects to the data server.

单项选择题Given the following table definitions: EMPLOYEE ID NAME DEPTID 01Smith 10 02Bossy 20 03 20 Peterson 04Goss 30 05Pape 40 06Avery 50 07ONeal 60 08Carter 50 DEPARTMENT ID DEPTNAME 05 Hardware 10 Kitchen 20 Shoes 30 Toys 40 Electronics 50 Automotive and the following query: SELECT e.id, d.deptname FROM employee e, department d WHERE e.deptid = d.id AND e.id > 4 Which of the following queries will produce the same result set as the query above?（）

A.SELECT e.id, d.deptname FROM employee e, department d WHERE e.id > 4
B.SELECT e.id, d.deptname FROM employee e INNER JOIN department d ON e.deptid = d.id WHERE e.id > 4
C.SELECT e.id, d.deptname FROM employee e FULL OUTER JOIN department d ON e.id = d.id WHERE e.id > 4
D.SELECT e.id, d.deptname FROM employee e LEFT OUTER JOIN department d ON e.deptid = d.id WHERE e.id > 4 UNION ALL SELECT e.id, d.deptname FROM employee e RIGHT OUTER JOIN department d ON e.deptid = d.id WHERE e.id > 4