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databases Online Quiz - 157

Description: databases Online Quiz - 157
Number of Questions: 20
Created by:
Tags: databases
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Explicit Defaults can be used in

technology databases

  1. INSERT statement

  2. UPDATE statement

  3. Both of the Above

  4. None of the Above

Show answer
Correct Option: C

MERGE statement

technology databases

  1. Avoids separate updates

  2. ncreases performance and ease of use

  3. Is useful in data warehousing applications

  4. All of the above

Show answer
Correct Option: D

Database transactions end with

technology databases

  1. COMMIT or ROLLBACK

  2. A DDL or DCL statement executing

  3. USER exiting iSQL*Plus or System crash

  4. Any one of the above

Show answer
Correct Option: D

In an Oracle Database, Locks are critical

technology databases

  1. True

  2. False

Show answer
Correct Option: B

Which is not a group function?

technology databases

  1. Count

  2. Avg

  3. Total

  4. Max

Show answer
Correct Option: C

AI Explanation

To answer this question, you need to understand the concept of group functions in SQL. Group functions are used to perform calculations on groups of rows rather than individual rows in a table.

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

Option A) Count - This option is a group function. It is used to count the number of rows that match a specific condition.

Option B) Avg - This option is a group function. It is used to calculate the average value of a column in a group of rows.

Option C) Total - This option is not a standard group function in SQL. The correct group function for calculating the total sum of a column is called "Sum". Therefore, option C is the correct answer to the question.

Option D) Max - This option is a group function. It is used to find the maximum value of a column in a group of rows.

The correct answer is C) Total. This option is not a group function in SQL, whereas the other options (A, B, and D) are valid group functions.

You can use Avg or Sum group functions for any numeric data

technology databases

  1. True

  2. False

Show answer
Correct Option: B

COUNT(DISTINCT expr) returns

technology databases

  1. No. of rows in a table

  2. No. of rows with non-null values of the expr

  3. No. of distinct non-null values of the expr

  4. None of the above

Show answer
Correct Option: C

Which function forces group functions to include null values?

technology databases

  1. Group By

  2. NVL

  3. Order By

  4. Having

Show answer
Correct Option: B

All columns in the SELECT list, that are not there in the GROUP function, should be in the Group By clause

technology databases

  1. True

  2. False

Show answer
Correct Option: B

Which is the clause used to restrict groups?

technology databases

  1. HAVING

  2. WHERE

  3. Order By

  4. Group by

Show answer
Correct Option: A

We can use Group functions in the WHERE clause

technology databases

  1. True

  2. False

Show answer
Correct Option: B

We can use MIN and MAX for any

technology databases

  1. Numeric data

  2. Data type

  3. Char data

  4. None of the Above

Show answer
Correct Option: A

You can update more than 1 row in a table with one update syntax

technology databases

  1. True

  2. False

Show answer
Correct Option: B

Delete from Employee where grade = ‘Y’” deletes

technology databases

  1. All rows of the Employee table

  2. Rows of the Employee table where the set grade is ‘Y’

  3. Delete 1 row

  4. Nothing will be deleted

Show answer
Correct Option: B

Which keyword used in DML statements prohibits you from changing rows that are not in the sub-query?

technology databases

  1. CHECK keyword

  2. WITH CHECK keyword

  3. WITH CHECK OPTION keyword

  4. None of the Above

Show answer
Correct Option: C

Explicit Defaults can be used in

technology databases

  1. INSERT statement

  2. UPDATE statement

  3. Both of the Above

  4. None of the Above

Show answer
Correct Option: C

MERGE statement

technology databases

  1. Avoids separate updates

  2. ncreases performance and ease of use

  3. Is useful in data warehousing applications

  4. All of the above

Show answer
Correct Option: D

Database transactions end with

technology databases

  1. COMMIT or ROLLBACK

  2. A DDL or DCL statement executing

  3. USER exiting iSQL*Plus or System crash

  4. Any one of the above

Show answer
Correct Option: D

In an Oracle Database, Locks are critical

technology databases

  1. True

  2. False

Show answer
Correct Option: B

Which is not a group function?

technology databases

  1. Count

  2. Avg

  3. Total

  4. Max

Show answer
Correct Option: C
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