NULL Comparisons

In SQL, comparisons involving NULL values yield NULL results rather than TRUE or FALSE. This behavior can lead to confusion if not properly understood. For instance:

sqlCopy codeSELECT * FROM employees WHERE salary = NULL;

This query will not return any records, as comparing any value with NULL does not yield TRUE. To check for NULL values effectively, you must use the IS NULL or IS NOT NULL operators. For example:

sqlCopy codeSELECT * FROM employees WHERE salary IS NULL;

This retrieves all employees whose salary is not defined. Handling NULLs correctly is critical for ensuring data integrity, as they can significantly impact analytical results and reporting. Analysts often encounter NULL values in datasets, making it essential to incorporate NULL handling in queries to provide comprehensive data assessments. Being adept at managing NULL comparisons allows users to draw more accurate conclusions and maintain the quality of their data analyses.