IS NULL and IS NOT NULL

The IS NULL and IS NOT NULL operators are essential tools for handling NULL values in Oracle SQL. NULLs represent missing or undefined data, and SQL treats them differently than standard values. The IS NULL operator is specifically designed to check for NULL values within a column. For example:

sqlCopy codeSELECT * FROM employees WHERE salary IS NULL;

This query retrieves all employees whose salary entries are NULL, which can be critical for identifying records with incomplete data. Conversely, IS NOT NULL serves the opposite purpose by filtering out records that contain NULL values. For example:

sqlCopy codeSELECT * FROM employees WHERE salary IS NOT NULL;

This query retrieves all employees with defined salary values. Effectively managing NULLs is crucial for data integrity, as they can impact analysis and reporting. Analysts often encounter NULLs in datasets, making it important to incorporate these operators in queries to ensure comprehensive data assessments. Understanding how to work with NULL values can significantly improve the accuracy and reliability of results in any SQL operation.