MySQL - Handling NULL Values MCQ

MySQL – Handling NULL Values MCQ

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1. What does a NULL value represent in MySQL?

Default value

Missing or unknown data

Empty string

Zero

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2. In MySQL, which operator is used to check if a column contains NULL values?

IS NULL

IS NOT NULL

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3. What is the purpose of the IS NOT NULL operator in MySQL?

Check for zero values

Check for default values

Check for missing data

Check for empty values

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4. Which MySQL function returns the first non-NULL value from a list of expressions?

IFNULL()

NULLSAFE()

REPLACE()

COALESCE()

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5. How can the COALESCE() function be used in MySQL?

To retrieve NULL values

To check for NULL values

To insert NULL values

To replace NULL values

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6. What does the IFNULL() function in MySQL do?

Checks for empty values

Checks for zero values

Returns NULL values

Returns the first non-NULL value

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7. What is the purpose of the NULL-safe equality operator (<=>) in MySQL?

Compares datetime values

Compares NULL values

Compares numeric values

Compares strings

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8. Which operator in MySQL treats two NULL values as equal?

<=>

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9. In MySQL, how are NULL values typically treated when using aggregate functions like SUM() or AVG()?

They are treated as empty strings

They are counted as zero

They cause an error

They are ignored

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10. What is the primary use of data validation in MySQL when dealing with NULL values?

To prevent NULL values

To count NULL values

To aggregate NULL values

To replace NULL values

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11. Which MySQL statement is used to enforce constraints on columns to prevent the insertion of NULL values?

CREATE TABLE

INSERT CONSTRAINTS

NOT NULL constraint

ALTER TABLE

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12. What is the purpose of providing default values for columns in MySQL?

To replace NULL values

To count NULL values

To insert NULL values

To prevent NULL values

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13. Which best practice should be followed to minimize the presence of NULL values in MySQL databases?

Use NULL as the default value

Normalize data

Avoid constraints

Use default values

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14. In MySQL, how can you effectively document the meaning of NULL values in your database schema?

Use data dictionaries

Normalize data

Avoid using NULL values

Use default values

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15. When should the IS NULL and IS NOT NULL operators be used in MySQL queries?

To filter rows based on NULL values

Exclusively in SELECT statements

To add new data

To enforce constraints

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16. What is the primary role of the BEGIN, COMMIT, and ROLLBACK statements in MySQL transaction management?

Data retrieval

Error handling

Data validation

Ensuring data consistency

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17. What is the purpose of using the principle of least privilege when handling NULL values in MySQL?

Security enhancement

Data encryption

Data retrieval

Data validation

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18. Which MySQL function can be used to replace NULL values with alternative values in queries or calculations?

IS NULL

IFNULL()

DEFAULT()

COALESCE()

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19. How are NULL values typically treated when performing string comparisons in MySQL?

As numeric values

As empty strings

As zero values

As NULL values

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20. In MySQL, what is the primary benefit of using the NULL-safe equality operator (<=>) in comparisons?

Simplifying queries

Avoiding data validation

Handling default values

Treating NULLs as equal

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21. Which data modification statement in MySQL can be used to replace NULL values with default values?

DELETE

UPDATE

REPLACE

INSERT

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22. How can data validation rules be implemented in a MySQL database to prevent the insertion of NULL values?

Use triggers

Use indexes

Use data dictionaries

Use constraints

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23. What is the primary benefit of using the IFNULL() function in MySQL when handling NULL values?

Providing default values

Handling empty values

Handling unknown data

Handling zero values

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24. Which MySQL function is used to return a specified value if a column contains NULL; otherwise, it returns the column’s value?

DEFAULT()

SUBSTITUTE()

IFNULL()

COALESCE()

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25. How can the COALESCE() function in MySQL be useful when working with query results?

To concatenate strings

To handle NULL values

To aggregate results

To return empty results

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