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databases Online Quiz - 119

Description: databases Online Quiz - 119
Number of Questions: 20
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Tags: databases
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Archived Redo Log is

technology databases

  1. It consists of Redo Log files that have archived before being reused.

  2. It consists of Redo Log files that have archived after being reused.

  3. It consists of Redo Log files that is archiving when currently being reused.

  4. It consists of Redo Log files that have archived not being reused.

Show answer
Correct Option: A

Examine the syntax for creating a DEPARTMENT table: CREATE TABLE ABCD( A NUMBER(4), B VARCNAR2(30), C NUMBER(6), D NUMBER(4)) STORAGE(INITIAL 200K NEXT 200K PCTINCREASE 50 MINEXTENTS 1 MAXEXTENTS 5) TABLESPACE userdata; What is the size defined for the fifth extent?

technology databases

  1. 500K

  2. 300K

  3. 675K

  4. 275K

Show answer
Correct Option: C

The control file defines the current state of the physical database. Which dynamic performance views obtain information from the control file?

technology databases

  1. V$LOG

  2. V$THREAD

  3. V$DATAFILE

  4. All of the above

Show answer
Correct Option: D

Control file contains information about

technology databases

  1. database

  2. redo logfile & datafile

  3. archivelog file location

  4. All of the above

Show answer
Correct Option: D

What is a Parallel Server

technology databases

  1. Multiple instances accessing the same database (Only In Multi-CPU environments)

  2. Multiple instances accessing the same database (Only In single-CPU environments)

  3. Multiple instances accessing the different database (Only In single-CPU environments)

  4. Single instance accessing the multiple database (Only In Multi-CPU environments)

Show answer
Correct Option: A

To re-create a database, all existing database files should be reused. The following SQL statement is issued: CREATE DATABASE ABC DATAFILE '/u01/oradata/abc/system0l.dbf' SIZE 100M REUSE LOGFILE GROUP 1 ('/u01/oradata/abc/logla.rdo', '/u02/oradata/abc/loglb.rdo') SIZE 50K REUSE, GROUP 2 ('/u01/oradata/abc/log2a.rdo', '/u02/oradata/abc/log2b.rdo') SIZE 50K REUSE MAXLOGFILES 5 MAXLOGHISTORY 100 MAXDATAFILES 10; Why does the CREATE DATABASE statement fail?

technology databases

  1. The MAXLOGFILES are set too low

  2. The CONTROLFILE REUSE clause is omitted

  3. The online redo log files cannot be reused

  4. The data file belonging to the SYSTEM tablespace cannot be reused

Show answer
Correct Option: B

What represents the value of the ORACLE_HOME environment variable in Oracle 9i?

technology databases

  1. @

  2. !

  3. ^

  4. &

Show answer
Correct Option: A

Which of the following tasks can be performed by using the TO_CHAR function?

technology databases

  1. Convert '10'to 10

  2. Convert 'TEN' to 10

  3. Convert 10 to '10'

  4. Convert a character expression to a date

Show answer
Correct Option: C

Evaluate the following SQL statement: SELECT ROUND (TRUNC (MOD (1600, 10),-1), 2) FROM dual; What will be displayed?

technology databases

  1. 100

  2. 0

  3. 1

  4. 10

Show answer
Correct Option: B
Explanation:

To understand the given SQL statement, the user must know the following functions:

  1. MOD - returns the remainder of a division operation
  2. TRUNC - truncates a number to a specified number of decimal places
  3. ROUND - rounds a number to a specified number of decimal places

Now let's break down the SQL statement:

  • The MOD function calculates the remainder of 1600 divided by 10, which is 0.
  • The TRUNC function truncates 0 to -1 decimal places, which is still 0.
  • Finally, the ROUND function rounds 0 to 2 decimal places, which is still 0.

Therefore, the answer is option B: 0.

What is the effect of setting the value "ALL_ROWS" for OPTIMIZER_GOAL parameter of the ALTER SESSION command ?

technology databases

  1. This value causes the optimizer to the rule-based approach for all SQL statements in the session regardless of the presence of statistics and to optimize with a goal of best throughput

  2. This value causes the optimizer to the rule-based approach for all SQL statements in the session in regard of the presence of statistics and to optimize with a goal of best throughput

  3. This value causes the optimizer to the cost-based approach for all SQL statements in the session regardless of the presence of statistics and to optimize with a goal of best throughput

  4. This value causes the optimizer to the cost-based approach for all SQL statements in the session regard of the presence of statistics and to optimize with a goal of best throughput

Show answer
Correct Option: C

What is the correct use of the Trunc command on a date?

technology databases

  1. SELECT TRUNC(TO_DATE('12-Feb-99','DD-MON-YY'), 'YEAR') "Date " FROM DUAL;

  2. SELECT TRUNC(TO_DATE('12-Feb-99','DD-MON-YY'), 'YEAR') FROM DUAL;

  3. TRUNCATE=To_Date('09-Jan-02,DD-MON-YY,'YEAR',"Date" from Dual;

  4. Date =TRUNCATE(To_DATE('09-Jan-02','DD-MON-YY'),'YEAR'),'YEAR)"DATE: from DUAL;

Show answer
Correct Option: A

How do I eliminate duplicate rows in an Oracle database?

technology databases

  1. DELETE FROM table_name WHERE ROWID IN (SELECT MAX (ROWID) FROM table_name GROUP BY duplicate_values_field_name);

  2. DELETE FROM table_name WHERE ROWID NOT IN (SELECT MAX (ROWID) FROM table_name GROUP BY duplicate_values_field_name);

  3. DELETE FROM table_name WHERE ROWID IN (SELECT MIN (ROWID) FROM table_name GROUP BY duplicate_values_field_name);

  4. DELETE FROM table_name WHERE ROWID IN (SELECT AVG (ROWID) FROM table_name GROUP BY duplicate_values_field_name);

Show answer
Correct Option: B

Which Oracle access method is the fastest way for Oracle to retrieve a single row?

technology databases

  1. Primary key access

  2. Access via unique index

  3. Table access by ROWID

  4. Full table scan

Show answer
Correct Option: C

Which command will delete all data from a table and will not write to the rollback segment?

technology databases

  1. DROP

  2. DELETE

  3. CASCADE

  4. TRUNCATE

Show answer
Correct Option: D

AI Explanation

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

Option A) DROP - This option is incorrect because the DROP command is used to delete an entire table, including its structure, from the database. It does not delete data from a table without writing to the rollback segment.

Option B) DELETE - This option is incorrect because the DELETE command is used to delete specific rows from a table based on a condition. It does not delete all data from a table without writing to the rollback segment.

Option C) CASCADE - This option is incorrect because the CASCADE keyword is used in conjunction with the DROP command to delete dependent objects along with the table. It does not delete all data from a table without writing to the rollback segment.

Option D) TRUNCATE - This option is correct because the TRUNCATE command is used to delete all data from a table without writing to the rollback segment. It is a faster operation than DELETE as it does not generate undo logs for each deleted row.

The correct answer is D) TRUNCATE. This option is correct because it deletes all data from a table without writing to the rollback segment.

Which character function can be used to return a specified portion of a character string?

technology databases

  1. INSTR

  2. SUBSTRING

  3. SUBSTR

  4. POS

Show answer
Correct Option: C

Which of the following SQL functions can operate on any datatype?

technology databases

  1. TO_CHAR

  2. LOWER

  3. LPAD

  4. MAX

  5. CEIL

Show answer
Correct Option: D
Explanation:

The correct answer is D. MAX.

The MAX function in SQL can operate on any datatype. It is used to retrieve the maximum value from a column or a set of values. Regardless of the datatype of the column or the values, the MAX function will return the maximum value.

The other functions mentioned:

A. LOWER: It is used to convert a string to lowercase. It can only operate on string or text datatypes.

B. TO_CHAR: It is used to convert a value to a character string. It is typically used to convert a date or a number to a specific string format. It can operate on different datatypes but is primarily used for date and number conversions.

C. LPAD: It is used to pad a string with specified characters on the left side. It can only operate on string or text datatypes.

E. CEIL: It is used to round up a number to the nearest integer. It can only operate on numeric datatypes.

Therefore, out of all the options, only the MAX function can operate on any datatype.

Which of the following is an important consideration when tuning an SQL statement?

technology databases

  1. The number of CPUs on the server

  2. The degree of parallelism on the tables

  3. The use of bitmap indexes

  4. The quality of the SQL optimization

Show answer
Correct Option: D

AI Explanation

To answer this question, you need to understand the concept of tuning an SQL statement. Let's go through each option to understand why it is correct or incorrect:

Option A) The number of CPUs on the server - This option is incorrect because the number of CPUs on the server does not directly affect the tuning of an SQL statement. The number of CPUs may impact the overall performance of the server, but it is not a specific consideration for tuning an SQL statement.

Option B) The degree of parallelism on the tables - This option is incorrect because the degree of parallelism on the tables also does not directly affect the tuning of an SQL statement. The degree of parallelism determines how many parallel execution servers are used to process a SQL statement, but it does not specifically relate to tuning the statement.

Option C) The use of bitmap indexes - This option is incorrect because the use of bitmap indexes is a consideration for indexing strategies, but it is not directly related to tuning an SQL statement. Bitmap indexes can improve the performance of certain queries, but they do not specifically address the tuning of an SQL statement.

Option D) The quality of the SQL optimization - This option is correct because the quality of the SQL optimization is an important consideration when tuning an SQL statement. SQL optimization involves analyzing the query execution plan, indexing strategies, statistics, and other factors to improve the performance of the SQL statement. Tuning the SQL statement involves optimizing the query execution plan and making changes to the SQL code to improve its efficiency.

The correct answer is D) The quality of the SQL optimization. This option is correct because it highlights the importance of optimizing the SQL statement to improve its performance.

What best describes the relationship between indexes and SQL performance?

technology databases

  1. Indexes are only used in special cases

  2. Indexes are used to make table storage more efficient

  3. Indexes rarely make a difference in SQL performance

  4. Indexes exist solely to improve query speed

Show answer
Correct Option: D
Explanation:

To understand the relationship between indexes and SQL performance, the user needs to know that indexes are used to improve the performance of queries that search large tables.

Now, let's go through each option and explain why it is right or wrong:

A. Indexes are only used in special cases: This option is incorrect. Indexes are commonly used in SQL databases to improve query performance, not just in special cases.

B. Indexes are used to make table storage more efficient: This option is partially correct. Indexes help make table storage more efficient by allowing for faster searching of the data, but their main purpose is to improve query performance.

C. Indexes rarely make a difference in SQL performance: This option is incorrect. Indexes can make a significant difference in the performance of SQL queries, especially when dealing with large tables.

D. Indexes exist solely to improve query speed: This option is partially correct. The primary purpose of indexes is to improve query speed, but they also help with other aspects of database performance such as data storage and retrieval.

The Answer is: D

Which of the following SQL clauses is used to select data from 2 or more tables?

technology databases

  1. HAVING

  2. JOIN

  3. WHERE

  4. BETWEEN

Show answer
Correct Option: B

Which of the following commands cause a transaction to end?

technology databases

  1. DELETE

  2. ALTER

  3. INSERT

  4. UPDATE

  5. ROLLBACK

Show answer
Correct Option: E
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