HqMra Blog

duminică, 4 aprilie 2010

Test: Quiz: Single-Row Subqueries

Section 1

1. Subqueries are limited to four per SQL transaction. True or False? Mark for Review
(1) Points

True

False (*)

2. In a non-correlated subquery, the outer query always executes prior to the inner query's execution. True or False? Mark for Review
(1) Points

True

False (*)

3. Single row subqueries may not include this operator: Mark for Review
(1) Points

ALL (*)

=

<>

>

4. The result of this statement will be:

SELECT last_name, job_id, salary, department_id
FROM employees
WHERE job_id =
(SELECT job_id
FROM employees
WHERE employee_id = 141) AND department_id =
(SELECT department_id
FROM departments
WHERE location_id =1500)
Mark for Review
(1) Points

All employees from Location 1500 will be displayed

An error since you canﾒt get data from two tables in the same subquery

All employees with the department id of 141

Only the employees whose job id matches employee 141 and who work in location 1500 (*)

5. If the subquery returns no rows will the outer query return any values? Mark for Review
(1) Points

No, because you are not allowed to not return any rows from a subquery

Yes. It will just run and ignore the subquery

No, because the subquery will be treated like a null value. (*)

Yes, Oracle will find the nearest value and rewrite your statement implicitly when you run it

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Test: Quiz: Subqueries

Section 1

1. What will the following statement return:

SELECT employee_id, last_name
FROM employees
WHERE salary =
(SELECT MIN(salary)
FROM employees
GROUP BY department_id);

Mark for Review
(1) Points

Nothing. It is an invalid statement. (*)

A list of last_names and salaries of employees

A list of first_names and salaries of employees in Department 50

A list of last_names and salaries of employees grouped by department_id.

2. What will the following statement return:

SELECT last_name, salary
FROM employees
WHERE salary < (SELECT salary
FROM employees
WHERE employee_id = 103)
Mark for Review
(1) Points

A list of last_names and salaries of employees that makes more than employee 103

A list of last_names and salaries of employees that makes less than employee 103 (*)

A list of first_names and salaries of employees making less than employee 103

Nothing. It is an invalid statement.

3. What will the following statement return:

SELECT last_name, salary
FROM employees
WHERE (department_id, job_id) IN (SELECT (department_id, job_id)
FROM employees
WHERE employee_id = 103)
Mark for Review
(1) Points

A list of last_names and salaries of employees that works in the same department and has the same job_id as that of employee 103. (*)

A list of last_names or salaries of employees that works in the same department and has the same job_id as that of employee 103.

A list of last_names and salaries of employees that works in the same department or has the same job_id as that of employee 103.

Nothing. It is an invalid statement.

4. Which of the following statements is a true guideline for using subqueries? Mark for Review
(1) Points

Do not enclose the subquery in parentheses.

Place the subquery on the left side of the comparison condition.

The outer and inner queries can reference more than one table. They can get data from different tables. (*)

Only one WHERE clause can be used for a SELECT statement, and if specified, it must be the outer query.

5. Subqueries can only be placed in the WHERE clause. True or False? Mark for Review
(1) Points

True

False (*)

6. Examine the following statement:

SELECT last_name, salary
FROM employees
WHERE department_id = (SELECT department_id
FROM employees
WHERE employee_id = 103) AND job_id = (SELECT job_id
FROM employees
WHERE employee_id = 103)

Is this a pair-wise or non-pair-wise Subquery?
Mark for Review
(1) Points

This is an example of a non-pair-wise subquery. (*)

This is an example of a pair-wise subquery.

Neither. This statement is illegal, and will not run.

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Test: Quiz: Group By and Having Clauses, ROLLUP and CUBE Operations, and Grouping Sets

Section 1

1. Which of the following SQL statements could display the number of people with the same last name: Mark for Review
(1) Points

SELECT first_name, last_name, COUNT(employee_id)
FROM EMPLOYEES
GROUP BY last_name;

SELECT employee_id, COUNT(last_name)
FROM EMPLOYEES
GROUP BY last_name;

SELECT last_name, COUNT(last_name)
FROM EMPLOYEES
GROUP BY last_name;

(*)

SELECT employee_id, DISTINCT(last_name)
FROM EMPLOYEES
GROUP BY last_name;

2. The use of GROUP BY GROUPING SETS(....) can speed up the execution of complex report statements? (True or False) Mark for Review
(1) Points

True (*)

False

3. The following is a valid statement:

SELECT MAX(AVG(salary))
FROM employees
GROUP BY department_id;

True or False?
Mark for Review
(1) Points

True (*)

False

4. Read the following SELECT statement. Choose the column or columns that must be included in the GROUP BY clause.

SELECT COUNT(last_name), grade, gender
FROM STUDENTS
GROUP_BY ?????;
Mark for Review
(1) Points

last_name

last_name, grade

grade, gender (*)

last_name, gender

5. Examine the following statement:

SELECT department_id, manager_id, job_id, SUM(salary)
FROM employees
GROUP BY GROUPING SETS((department_id, manager_id), (department_id, job_id))

What data will this query generate?

Mark for Review
(1) Points

Total salaries for (department_id, job_id) and (department_id, manager_id) (*)

Total salaries for (department_id, job_id, manager_id)

Total for (job_id, manager_id)

The statement will fail.

6. If you want to include subtotals and grant totals for all columns mentioned in a GROUP BY clause you should use which of the following extensions to the GROUP BY clause? Mark for Review
(1) Points

ROLLUP

CUBE (*)

GROUP BY ALL COLUMNS

HAVING

7. Is the following statement correct?

SELECT department_id, AVG(salary)
FROM employees;

Mark for Review
(1) Points

No, because a GROUP BY department_id clause is needed (*)

No, because the SELECT clause cannot contain both individual columns and group functions

No, because the AVG function cannot be used on the salary column

Yes

8. Examine the following statement:

SELECT department_id, manager_id, job_id, SUM(salary)
FROM employees
GROUP BY GROUPING SETS(.......);

Select the correct GROUP BY GROUPING SETS clause from the following list:

Mark for Review
(1) Points

GROUP BY GROUPING SETS (department_id, AVG(salary)), (department_id, job_id), (department_id, manager_id)

GROUP BY GROUPING SETS (department_id, salary), (department_id, job_id), (department_id, manager_id)

GROUP BY GROUPING SETS ((department_id, manager_id), (department_id, job_id), (manager_id, job_id)) (*)

GROUP BY GROUPING SETS ((department_id, manager_id), (department_id, SUM(salary), (manager_id, job_id))

9. How would you alter the following query to list only employees where more than one employee exists with the same last_name:

SELECT last_name, COUNT(employee_id)
FROM EMPLOYEES
GROUP BY last_name;

Mark for Review
(1) Points

SELECT last_name, COUNT(employee_id)
FROM EMPLOYEES
WHERE COUNT(*) > 1
GROUP BY last_name

SELECT last_name, COUNT(last_name)
FROM EMPLOYEES
GROUP BY last_name
HAVING COUNT(last_name) > 1;

(*)

SELECT last_name, COUNT(last_name)
FROM EMPLOYEES
GROUP BY last_name
EXISTS COUNT(last_name) > 1;

SELECT employee_id, DISTINCT(last_name)
FROM EMPLOYEES
GROUP BY last_name
HAVING last_name > 1;

10. Is the following statement correct:

SELECT first_name, last_name, salary, department_id, COUNT(employee_id)
FROM employees
WHERE department_id = 50
GROUP BY last_name, first_name, department_id;

Mark for Review
(1) Points

Yes

No, beause you cannot have a WHERE-clause when you use group functions.

No, because the statement is missing salary in the GROUP BY clause (*)

Yes, because Oracle will correct any mistakes in the statement itself

11. Examine the following statement:

SELECT department_id, manager_id, job_id, SUM(salary)
FROM employees
GROUP BY ROLLUP(department_id, manager_id)

What extra data will this query generate?

Mark for Review
(1) Points

Subtotals for department_id, and grand totals for salary.

Subtotals for department_id, job_id and grand totals for salary.

Subtotals for department_id, job_id, manager_id and grand totals for salary.

The statement will fail. (*)

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joi, 4 martie 2010

The Piano - Amazing Short

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NASA a pozat o... "gorila" extraterestra!

Se pare ca cei de la NASA au inceput sa "vaneze maimute" pe Marte :)). Eu unu ma mir ca n'au vazut iepuri :)) sau vreun elefant :)))

Internautii sunt convinsi ca nu este vorba de o stanca de genul Sfinxului din Bucegi, cum ati fi tentati sa credeti.

De exemplu, Nigel Cooper, in varsta de 43 de ani, a declarat ca este sigur ca NASA a surprins o entitate vie si e absolut convins ca pe Marte exista deja forme de viata evoluate.

Voi ce credeti? este o gorila? Sau iar s'a jucat cineva in photoshop ? :))

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