How do you handle NULL values in SQL Server?
Methods for handling NULL values in SQL Server include:
- Use the IS NULL and IS NOT NULL operators to determine if a value is NULL.
For example:
SELECT * FROM table_name WHERE column_name IS NULL; - Replace NULL values with a specified default value using the COALESCE function. For example: SELECT COALESCE(column_name, ‘default_value’) FROM table_name;
- Utilize a CASE statement to handle NULL values, deciding what value should be taken based on certain conditions. For example: SELECT CASE WHEN column_name IS NULL THEN ‘default_value’ ELSE column_name END FROM table_name;
- Use the IFNULL function to replace NULL values with a specified default value.
For example:
SELECT IFNULL(column_name, ‘default_value’) FROM table_name; - Use the NULLIF function to replace a specified value with NULL.
For example:
SELECT NULLIF(column_name, ‘value_to_replace’) FROM table_name;
By using the above method, NULL values encountered in SQL Server can be effectively handled.