Which function would you use to replace NULLs with a specified value?

Which function would you use to replace NULLs with a specified value?

• A. CAST
• B. Trim
• C. COALESCE
• D. Between

Answer: (C)

Replacing NULLs with a specified value is done with a function that returns the first non-NULL value from its arguments. The best choice is COALESCE, because COALESCE(column, default_value) yields the column’s value when it isn’t NULL, and substitutes the default_value when it is NULL. This makes it a simple and reliable way to ensure you have a usable value in results or computations. For example, COALESCE(salary, 0) will show 0 wherever salary is NULL. Cast changes data types, not NULL handling. Trim removes leading or trailing spaces from strings, not substitute NULLs. Between checks whether a value lies in a range, not replace NULLs.

Replacing NULLs with a specified value is done with a function that returns the first non-NULL value from its arguments. The best choice is COALESCE, because COALESCE(column, default_value) yields the column’s value when it isn’t NULL, and substitutes the default_value when it is NULL. This makes it a simple and reliable way to ensure you have a usable value in results or computations. For example, COALESCE(salary, 0) will show 0 wherever salary is NULL.

Cast changes data types, not NULL handling. Trim removes leading or trailing spaces from strings, not substitute NULLs. Between checks whether a value lies in a range, not replace NULLs.