What are the best practices for handling NULL values in SQL?

What are the best practices for handling NULL values in SQL?

Handling NULL values in SQL is crucial for data integrity. Here are some best practices: 1. Use IS NULL and IS NOT NULL for checks. 2. Avoid using NULL in primary keys. 3. Use default values where appropriate. 4. Consider using COALESCE to provide fallback values.

Can you explain why NULLs can be problematic in SQL?

NULLs can lead to unexpected results in queries, especially with aggregate functions. They can also complicate joins and comparisons, making it harder to ensure data accuracy.

What functions can I use to handle NULL values effectively?

You can use functions like COALESCE, NULLIF, and ISNULL. COALESCE returns the first non-null value, NULLIF returns NULL if two expressions are equal, and ISNULL checks if a value is NULL.

Are there any performance considerations when dealing with NULLs?

Yes, NULLs can affect performance, especially in indexing. Queries with NULLs may not utilize indexes effectively, leading to slower performance. It's best to minimize their use in indexed columns.