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databases Online Quiz - 115

Description: databases Online Quiz - 115
Number of Questions: 20
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Tags: databases
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You are defining the operational process of your RDBMS. Referring to the scenario above, which one of the following is a valid ongoing "operational process?"

  1. OS requirement

  2. User analysis

  3. Performance monitoring

  4. Data dictionary specification

  5. System requirement


Correct Option: C

AI Explanation

To answer this question, you need to understand the operational processes involved in a Relational Database Management System (RDBMS). Let's go through each option to understand why it is correct or incorrect:

Option A) OS requirement - This option is not a valid ongoing operational process. OS requirement refers to the specific operating system required to run the RDBMS, which is determined during the initial setup or installation of the system, rather than an ongoing process.

Option B) User analysis - This option is not a valid ongoing operational process. User analysis typically occurs during the initial stages of designing and implementing the RDBMS to understand the needs and requirements of the users, but it is not an ongoing process.

Option C) Performance monitoring - This option is a valid ongoing operational process. Performance monitoring involves continuously monitoring and analyzing the performance of the RDBMS, identifying any issues or bottlenecks, and making necessary adjustments to optimize the system's performance.

Option D) Data dictionary specification - This option is not a valid ongoing operational process. Data dictionary specification refers to defining the structure and metadata of the data stored in the RDBMS, which is typically done during the initial design and setup of the system.

Option E) System requirement - This option is not a valid ongoing operational process. System requirement refers to the overall requirements and specifications of the RDBMS, which are determined during the initial stages of designing and implementing the system.

The correct answer is C) Performance monitoring. This option is correct because monitoring the performance of the RDBMS is an ongoing process that ensures the system is running efficiently and effectively.

You have been asked to construct a query in the company's RDBMS. You have deployed a Right Outer Join operation. Referring to the scenario above, what will happen to the final results when there is NO match between the tables?

  1. The right table will return ALL rows.

  2. The right table will return NULL.

  3. Both tables will return NULL.

  4. The left table will return ALL rows.

  5. The left table will return NULL.


Correct Option: D

AI Explanation

To answer this question, we need to understand the behavior of a Right Outer Join operation when there is no match between the tables.

In a Right Outer Join, all the rows from the right table are returned, regardless of whether there is a match or not. If there is no match between the tables, the columns from the left table will have NULL values in the result set.

Therefore, the correct answer is:

D. The left table will return ALL rows.

This option is correct because in a Right Outer Join, when there is no match, the left table will still return all of its rows, but with NULL values in the columns that correspond to the right table.

Which phase of the data modeling process contains security review?

  1. Structure

  2. Design issue

  3. Data source

  4. Storage issue

  5. Operational process


Correct Option: B

AI Explanation

To answer this question, let's go through each option to understand why it is correct or incorrect:

Option A) Structure - This option is incorrect because the structure phase of the data modeling process typically focuses on organizing and defining the relationships between data entities, attributes, and their constraints. It does not specifically involve security review.

Option B) Design issue - This option is correct because the design issue phase of the data modeling process often includes a security review. During this phase, the data model is evaluated for potential security vulnerabilities, access controls, and encryption requirements. It ensures that the data model is designed to protect sensitive information.

Option C) Data source - This option is incorrect because the data source phase of the data modeling process typically involves identifying and gathering the necessary data from various sources. It does not specifically involve security review.

Option D) Storage issue - This option is incorrect because the storage issue phase of the data modeling process focuses on determining the most appropriate storage technologies and structures for the data. It does not specifically involve security review.

Option E) Operational process - This option is incorrect because the operational process phase of the data modeling process involves defining the processes and procedures for managing and maintaining the data model. It does not specifically involve security review.

The correct answer is B) Design issue. This option is correct because the design issue phase of the data modeling process often includes a security review to ensure the data model is designed with security considerations in mind.

Which one of the following is NOT a characteristic of metadata?

  1. Data about data

  2. Describes a data dictionary

  3. Self-describing

  4. Includes user data

  5. Supports its own structure


Correct Option: D

Which one of the following capabilities do you expect to see in a majority of RDBMS extensions to ANSI SQL-92?

  1. Encryption key management

  2. Graphical User Interface Widgets

  3. Thread creation, execution, & coordination

  4. Network socket creation/operation

  5. If/Then, for, do/while statements


Correct Option: E

What can a mandatory one to one relationship indicate?

  1. More entities are needed.

  2. The model should be denormalized.

  3. The tables are not properly indexed.

  4. The model cannot be implemented physically.

  5. More attributes are needed.


Correct Option: E

AI Explanation

To answer this question, we need to understand the concept of a mandatory one-to-one relationship in database modeling.

A mandatory one-to-one relationship indicates that each entity in one table must be associated with exactly one entity in another table, and vice versa. In other words, it means that every record in one table must have a corresponding record in the other table, and vice versa.

Let's go through each option to determine which one is correct:

Option A) More entities are needed - This option is incorrect. A mandatory one-to-one relationship does not imply that more entities are needed. It simply means that each entity in one table must have a corresponding entity in another table.

Option B) The model should be denormalized - This option is incorrect. A mandatory one-to-one relationship does not necessarily indicate that the model should be denormalized. Denormalization is a technique used to improve performance in certain situations, but it is not directly related to the presence of a mandatory one-to-one relationship.

Option C) The tables are not properly indexed - This option is incorrect. The presence of a mandatory one-to-one relationship does not necessarily indicate that the tables are not properly indexed. Indexing is a separate concept that is used to improve the performance of database queries.

Option D) The model cannot be implemented physically - This option is incorrect. A mandatory one-to-one relationship does not imply that the model cannot be implemented physically. It simply means that there is a requirement for a one-to-one relationship between entities in two tables.

Option E) More attributes are needed - This option is correct. A mandatory one-to-one relationship can indicate that more attributes are needed in either of the tables involved in the relationship. Since each entity in one table must be associated with exactly one entity in the other table, it may require additional attributes to properly capture the relationship.

Therefore, the correct answer is option E) More attributes are needed. This option is correct because a mandatory one-to-one relationship can indicate that additional attributes are needed in either of the tables involved in the relationship.

For performance, you denormalize your database design and create some redundant columns. Referring to the scenario above, what RDBMS construct can you use to automatically prevent the repeated columns from getting out of sync?

  1. Cursors

  2. Constraints

  3. Views

  4. Stored procedures

  5. Trigger


Correct Option: E

You are running a query against a relational database. Referring to the scenario above, what clause or command do you use in the query to help avoid a costly tablescan?

  1. GROUP BY clause

  2. INDEX command

  3. HAVING clause

  4. FROM clause

  5. WHERE clause [/quote]


Correct Option: B

AI Explanation

To answer this question, you need to understand how to optimize query performance in a relational database.

The correct answer is B) INDEX command.

The INDEX command is used to create an index on one or more columns of a table, which helps improve query performance by allowing the database to quickly locate the rows that satisfy a certain condition. When an index is created, the database creates a separate data structure that stores the indexed column(s) in a sorted order, making it faster to search for specific values.

The other options are incorrect:

A) GROUP BY clause - The GROUP BY clause is used to group rows that have the same values in specific columns. While it can help organize the data for aggregation functions, it does not directly optimize query performance.

C) HAVING clause - The HAVING clause is used to filter the results of a query based on a condition applied to the grouped data. Similar to the GROUP BY clause, it is used for data manipulation rather than optimization.

D) FROM clause - The FROM clause is used to specify the table(s) from which you want to retrieve data in a query. It does not directly optimize query performance.

E) WHERE clause - The WHERE clause is used to specify the conditions that must be met for a row to be included in the result set. While it can help filter the data, it does not directly optimize query performance.

Therefore, the correct answer is B) INDEX command because it is specifically used to improve query performance by creating an index on one or more columns of a table.

The query performance increases by using NOT operator.

  1. True

  2. False


Correct Option: B

If there are 3 persons with last names JOHN, J and JAMES how many of them are included in the result set of the query "SELECT LAST_NAME FROM STAFF WHERE LAST_NAME BETWEEN 'A' AND 'J'"

  1. 3

  2. 2

  3. 1

  4. 0


Correct Option: C

NULL values are ingnored for all SQ: 2008 aggregate functions.

  1. True

  2. False


Correct Option: A

Which operators can be used to produce summary totals in the result sets of SQL 2008.

  1. GROUPING

  2. WITH ROLL UP

  3. WITH CUBE

  4. WITH SUMMARY


Correct Option: B,C

UNION ALL is faster than a UNION

  1. True

  2. False


Correct Option: A

The query performance increases by using NOT operator.

  1. True

  2. False


Correct Option: B

NULL values are ingnored for all SQL: 2008 aggregate functions.

  1. True

  2. False


Correct Option: A
  1. STDDEV

  2. VARIANCE

  3. ROUND

  4. COUNT


Correct Option: C

which of this Operator Precedence is correct??

    • , + (Unary operators, negation)
    • , / (Multiplication, division)
  1. +, - , || (Addition, subtraction, concatenation)

  2. NONE of these


Correct Option: A,B,C

When you try to save 34567.2255 into a column defined as NUMBER(7,2) what value is actually saved?

  1. 34567.00

  2. 34567.22

  3. 34567.23

  4. 3456.22


Correct Option: C

AI Explanation

To answer this question, we need to understand how the NUMBER data type works in Oracle.

The NUMBER data type is used to store decimal numbers in Oracle. The format for the NUMBER data type is NUMBER(p, s), where p represents the precision and s represents the scale. The precision (p) is the total number of digits that can be stored in the column, and the scale (s) is the number of digits to the right of the decimal point.

In this case, the column is defined as NUMBER(7,2), which means it can store a total of 7 digits, with 2 digits to the right of the decimal point.

When we try to save the value 34567.2255 into this column, Oracle will round the value according to the specified scale. In this case, it will round the value to 2 decimal places.

So, the value that is actually saved in the column will be 34567.23.

Let's go through each option to understand why it is correct or incorrect:

Option A) 34567.00 - This option is incorrect because it does not take into account the rounding that occurs when saving the value into the column.

Option B) 34567.22 - This option is incorrect because it does not take into account the rounding that occurs when saving the value into the column.

Option C) 34567.23 - This option is correct because it correctly represents the value that is actually saved in the column, after rounding to 2 decimal places.

Option D) 3456.22 - This option is incorrect because it does not represent the value that is actually saved in the column.

The correct answer is C. The value that is actually saved in the column is 34567.23.

What is the default display length of the DATE datatype column?

  1. 8

  2. 9

  3. 6

  4. 16


Correct Option: B
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