多项选择题

Which two statements about subqueries are true? （）……

Which two statements about subqueries are true? （）

A. A single row subquery can retrieve data from only one table.
B. A SQL query statement cannot display data from table B that is referred to in its subquery, unless table B is included in the main query's FROM clause.
C. A SQL query statement can display data from table B that is referred to in its subquery, without including B in its own FROM clause.
D. A single row subquery can retrieve data from more than one table.
E. A single row subquery cannot be used in a condition where the LIKE operator is used for comparison.
F. A multiple-row subquery cannot be used in an INSERT statement to insert multiple rows at a time.

<上一题目录下一题>

热门试题

单项选择题Examine the structure of the EMPLOYEES table: EMPLOYEE_ID NUMBER Primary Key FIRST_NAME VARCHAR2(25) LAST_NAME VARCHAR2(25) HIRE_DATE DATE Which INSERT statement is valid? （）

A. INSERT INTO employees (employee_id, first_name, last_name, hire_date) VALUES (1000, 'John', 'smith','01/01/01);
B. INSERT INTO employees(employee_id, first_name, last_name, hire_date) VALUES (1000, 'John', 'smith','01 january 01');
C. INSERT INTO employees(employee_id, first_name, last_name, Hire_date) VALUES (1000, 'John', 'smith', To_ date ('01/01/01));
D. INSERT INTO employees(employee_id, first_name, last_name, hire_date) VALUES (1000, 'John', 'smith','01-Jan-01');

多项选择题Which are SQL*Plus commands? （）

A. INSERT
B. UPDATE
C. SELECT
D. DESCRIBE
E. DELETE
F. RENAME

单项选择题Examine the structure of the STUDENTS table: STUDENT_ID NUMBER NOT NULL, Primary Key STUDENT_NAME VARCHAR2(30) COURSE_ID VARCHAR2(10) NOT NULL MARKS NUMBER START_DATE DATE FINISH_DATE DATE You need to create a report of the 10 students who achieved the highest ranking in the course INT SQL and who completed the course in the year 1999. Which SQL statement accomplishes this task? （）

A. SELECT student_ id, marks, ROWNUM "Rank" FROM students WHERE ROWNUM <= 10 AND finish_date BETWEEN '01-JAN-99' AND '31-DEC-99 AND course_id = 'INT_SQL' ORDER BY mark DESC;
B. SELECT student_id, marks, ROWID "Rank" FROM students WHERE ROWID <= 10 AND finish_date BETWEEN '01-JAN-99' AND '31-DEC-99' AND course_id = 'INT_SQL' ORDER BY mark;
C. SELECT student_id, marks, ROWNUM "Rank" FROM (SELECT student_id, marks FROM students WHERE ROWNUM <= 10 AND finish_date BETWEEN '01-JAN-99' AND '31-DEC- 99' AND course_id = 'INT_SQL' ORDER BY mark DESC;
D. SELECT student_id, marks, ROWNUM "Rank" FROM (SELECT student_id, marks FROM students WHERE (finish_date BETWEEN '01-JAN-99 AND '31-DEC-99' AND course_id = 'INT_SQL' ORDER BY marks DESC) WHERE ROWNUM <= 10;
E. SELECT student id, marks, ROWNUM "Rank" FROM (SELECT student_id, marks FROM students ORDER BY marks) WHERE ROWNUM <= 10 AND finish date BETWEEN '01-JAN-99' AND '31-DEC-99' AND course _ id 'INT_SQL';

单项选择题Which statement correctly describes SQL and SQL*Plus? （）

A. Both SQL and /SQL*plus allow manipulation of values in the database.
B. /SQL* Plus recognizes SQL satement and sends them to the server; SQL is the Oracle proprietary interface for executing SQL statements.
C. /SQL* Plus language for communicating with the Oracle server to access data; SQL recognizes SQL statements and sends them to the server.
D. /SQL manipulates data and table definition in the database; /SQL* Plus does not allow manipulation of values in the database.

多项选择题Which two are true about aggregate functions?（）

A. You can use aggregate functions in any clause of a SELECT statement.
B. You can use aggregate functions only in the column list of the select clause and in the WHERE clause of a SELECT statement.
C. You can mix single row columns with aggregate functions in the column list of a SELECT statement by grouping on the single row columns.
D. You can pass column names, expressions, constants, or functions as parameter to an aggregate function.
E. You can use aggregate functions on a table, only by grouping the whole table as one single group.
F. You cannot group the rows of a table by more than one column while using aggregate functions.