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databases Online Quiz - 152

Description: databases Online Quiz - 152
Number of Questions: 20
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Tags: databases
Attempted 0/20 Correct 0 Score 0

When is a Cartesian product formed?

  1. When a join condition is omitted.

  2. When a join condition is invalid.

  3. All rows in the first table are joined to all rows in the second table.

  4. All of the above.


Correct Option: D

SYSDATE is a date function that returns the current database server date and time.

  1. True

  2. False


Correct Option: B

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

  1. CHECK keyword

  2. WITH CHECK keyword

  3. WITH CHECK OPTION keyword

  4. None of the Above


Correct Option: C
  1. INSERT statement

  2. UPDATE statement

  3. Both of the Above

  4. None of the Above


Correct Option: C

MERGE statement

  1. Avoids separate updates

  2. ncreases performance and ease of use

  3. Is useful in data warehousing applications

  4. All of the above


Correct Option: D
  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


Correct Option: D

COUNT(DISTINCT expr) returns

  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


Correct Option: C

Which function forces group functions to include null values?

  1. Group By

  2. NVL

  3. Order By

  4. Having


Correct Option: B
  1. HAVING

  2. WHERE

  3. Order By

  4. Group by


Correct Option: A

We can use Group functions in the WHERE clause

  1. True

  2. False


Correct Option: B

AI Explanation

To answer this question, you need to understand the purpose and usage of group functions and the WHERE clause in SQL.

Option A) True - This option is incorrect because group functions, also known as aggregate functions (e.g., SUM, AVG, COUNT), are typically used in the SELECT clause to perform calculations on a set of rows and return a single value. They cannot be used directly in the WHERE clause.

Option B) False - This option is correct because group functions cannot be used in the WHERE clause. The WHERE clause is used to filter rows based on specific conditions, such as column values. Group functions are used to perform calculations on a set of rows, typically in conjunction with the GROUP BY clause.

The correct answer is B. Group functions cannot be used in the WHERE clause.

We can use MIN and MAX for any

  1. Numeric data

  2. Data type

  3. Char data

  4. None of the Above


Correct Option: A
  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


Correct Option: B

In an Oracle Database, Locks are critical

  1. True

  2. False


Correct Option: B

Character values are case insensitive

  1. True

  2. False


Correct Option: B
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