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Technologies Experiences Contribute

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Data Types

1. What are the main categories of data types available in MySQL?

Level: Expert | Frequency: High

2. What is the difference between CHAR and VARCHAR data types?

Level: Expert | Frequency: High

3. Which data type would you use to store dates and times in MySQL?

Level: Expert | Frequency: High

4. What is the difference between INT, FLOAT, and DECIMAL data types?

Level: Expert | Frequency: High

5. What is the use of the TEXT and BLOB data types, and how are they different from VARCHAR?

Level: Expert | Frequency: High

6. How does MySQL handle precision and scale in DECIMAL(M, D) columns internally, and how do these differ from FLOAT and DOUBLE in terms of storage and accuracy?

Level: Expert | Frequency: High

7. When storing time zone–aware data, what are the differences in behavior and use cases between DATETIME, TIMESTAMP, and CONVERT_TZ() in MySQL?

Level: Expert | Frequency: High

8. If you define a VARCHAR(255) column with utf8mb4 encoding, how does MySQL calculate the maximum possible storage size for that column, and how does it differ from CHAR(255)?

Level: Expert | Frequency: High

9. What are the advantages and limitations of using ENUM and SET data types in terms of performance, flexibility, and schema evolution?

Level: Expert | Frequency: High

10. Explain how MySQL internally stores and sorts values of type BLOB and TEXT. What happens when you try to index a TEXT column?

Level: Expert | Frequency: High

11. How do signed and unsigned integer types affect query results, index usage, and storage size? Can you demonstrate an example where overflow behavior differs?

Level: Expert | Frequency: High

12. In what scenarios would using a JSON column be preferable to a normalized table structure, and what are the internal storage and indexing implications of JSON in MySQL 8.0?

Level: Expert | Frequency: High

13. How does MySQL’s BIT(M) type differ from BOOLEAN, TINYINT(1), and binary string types (BINARY, VARBINARY) in terms of storage, representation, and retrieval?

Level: Expert | Frequency: High

14. If you define a composite index on multiple columns of different data types (e.g., INT, VARCHAR, and DATE), how do the internal data type differences influence sorting, comparisons, and index efficiency?

Level: Expert | Frequency: High

15. What are the practical implications of using CHAR vs VARCHAR for columns in InnoDB tables with varying row lengths and frequent updates? How does this choice affect row fragmentation and performance?

Level: Expert | Frequency: High

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