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databases Online Quiz - 240

Description: databases Online Quiz - 240
Number of Questions: 20
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Tags: databases
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What is the Max size of NVARCHAR2 in PL/SQL?
technology databases

  1. 4000

  2. 8000

  3. 32768

  4. 32767

Show answer
Correct Option: D

What is the correct order to get a correct SQL statement?

technology databases

  1. SELECT FROM GROUP BY WHERE

  2. SELECT FROM GROUP BY ROLLUP

  3. SELECT GROUP BY FROM

  4. SELECT WHERE FROM GROUP BY

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Correct Option: B

NULL values violate CHECK constraint

technology databases

  1. True

  2. False

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Correct Option: B

Which of these operators is used to calculate super aggregate results?

technology databases

  1. ROLLUP

  2. COUNT

  3. AVG

  4. SUM

Show answer
Correct Option: A

Which is the syntax for enforcing the rule of deleting the dependent Foreign Key values on the deletion of a Primary Key?

technology databases

  1. ON DELETE SET NULL

  2. ON DELETE CASCADE

  3. ON DELETE DELETE

  4. ON DELETE RESTRICT

Show answer
Correct Option: B
Explanation:

To answer this question, the user needs to have knowledge of database management systems and the concept of Foreign Keys.

When a Foreign Key references a Primary Key in another table, there is a possibility that the referenced record(s) may be deleted. In such cases, four actions can be taken: SET NULL, CASCADE, DELETE, or RESTRICT.

  • ON DELETE SET NULL: This option sets the Foreign Key value to NULL when the referenced record(s) are deleted. This may lead to data integrity issues and is not ideal in most cases.

  • ON DELETE CASCADE: This option deletes all the dependent rows in the child table when the referenced rows in the parent table are deleted. This is usually the preferred option when the child rows are no longer relevant without the parent rows.

  • ON DELETE DELETE: This syntax does not exist, and hence, it is incorrect.

  • ON DELETE RESTRICT: This option prevents the deletion of the referenced rows in the parent table when there are dependent rows in the child table. This is useful when the data in the child table is still relevant and associated with the data in the parent table.

Therefore, the correct answer is:

The Answer is: B. ON DELETE CASCADE

UNION ALL has a comparitively faster performance compared to UNION?
technology databases

  1. True

  2. False

Show answer
Correct Option: A

Which of these is a String Aggregation function used to get values from different rows into a single column?
technology databases

  1. SUBSTR

  2. CON_STR

  3. CON_CAT

  4. WM_CONCAT

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Correct Option: D

TRANSLATE

technology databases

  1. Restricts the length of the String

  2. Replaces a sequence of characters in a string with another set of characters

  3. Modifies the datatype of a column

  4. Renames a column

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Correct Option: B

which of these can be used to filter aggregate functions?

technology databases

  1. WHEN

  2. HAVING

  3. WHERE

  4. ANY

Show answer
Correct Option: B

REPLACE

technology databases

  1. Replaces word by word

  2. Replaces a column with another column

  3. Replaces character by character

  4. Replaces a row with another row

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Correct Option: A

How is IN different form EXISTS ?

technology databases

  1. IN executes the inner query for each row affected by the outer query and EXISTS executes the inner query only once irrespective of the outer query

  2. IN executes the inner query only once irrespective of the outer query and EXISTS executes the inner query only once irrespective of the outer query

  3. IN executes the inner query only once irrespective of the outer query and EXISTS executes the outer query for each row affected by the outer query

  4. IN executes the inner query for each row affected by the outer query and EXISTS executes the outer query for each row affected by the outer query

Show answer
Correct Option: C

Teradata components handle data distribution by

technology databases

  1. AMP bucket number

  2. Primary Index

  3. Primary Key

  4. None of the above

Show answer
Correct Option: B

_____ and _____ are true about the Primary Index

technology databases

  1. Defined immediately after the table CREATE statement, used to find the Primary Key

  2. Defined during the table CREATE statement, used to assign rows to an AMP

  3. Defined immediately after the table CREATE statement, used to assign rows to an AMP

  4. Defined during the table CREATE statement, used to find the Primary Key

Show answer
Correct Option: B

_____ and _____ are true about the Primary Index

technology databases

  1. Defined immediately after the table CREATE statement, used to assign rows to an AMP

  2. Defined immediately after the table CREATE statement, used to find the Primary Key

  3. Defined during the table CREATE statement, used to assign rows to an AMP

  4. Defined during the table CREATE statement, used to find the Primary Key

Show answer
Correct Option: C

AI Explanation

To answer this question, you need to understand the concept of Primary Index in database management systems. Let's go through each option to understand why it is correct or incorrect:

Option A) Defined immediately after the table CREATE statement, used to assign rows to an AMP - This option is incorrect because the Primary Index is not used to assign rows to an AMP. The Primary Index is used to distribute the data across AMPs (Access Module Processors) in a Teradata database.

Option B) Defined immediately after the table CREATE statement, used to find the Primary Key - This option is incorrect because the Primary Index is not used to find the Primary Key. The Primary Key is a constraint that ensures uniqueness of a column or set of columns in a table.

Option C) Defined during the table CREATE statement, used to assign rows to an AMP - This option is correct. The Primary Index is defined during the table CREATE statement and is used to assign rows to an AMP. It determines how the data is distributed across the AMPs for efficient parallel processing.

Option D) Defined during the table CREATE statement, used to find the Primary Key - This option is incorrect because the Primary Index is not used to find the Primary Key.

The correct answer is C) Defined during the table CREATE statement, used to assign rows to an AMP. This option is correct because the Primary Index is defined during the table CREATE statement and is used to assign rows to an AMP.

A new table has been created in the employee. There are no rows in the table.What would be the output of the following query?select count(*) from employee

technology databases

  1. Error

  2. 1

  3. No data Found

  4. 0

Show answer
Correct Option: D

Which of the query will print the output as 'TCS' (single quotes should come in the output of the query)
technology databases

  1. select '''||'TCS'||''' from dual

  2. select 'TCS' from dual

  3. select '''TCS''' from dual

  4. select "TCS" from dual

Show answer
Correct Option: A

What's the output select to_Date('2009-may-25','yyyymmdd') from dual

technology databases

  1. 2009-may-25

  2. Error

  3. may-2009-25

  4. 200925may

Show answer
Correct Option: B

Which of the query will print the output as 'TCS' (single quotes should come in the output)

technology databases

  1. select '''||'TCS ||''' from dual

  2. select '''TCS''' from dual

  3. select "TCS" from dual

  4. select 'TCS' from dual

Show answer
Correct Option: B

Session Handling is done by which part of teradata system?

technology databases

  1. AMP

  2. PE

  3. BYNET

  4. CLIQUE

Show answer
Correct Option: B

TERADATA is Shared _________ architecture.

technology databases

  1. Nothing

  2. Everything

  3. Disk

  4. Processor

Show answer
Correct Option: A
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