COALESCE replaces NULL values with another value

COALESCE replaces NULL values with another value

• A. Trim
• B. Concatenating Strings
• C. CAST
• D. COALESCE

Answer: (D)

COALESCE returns the first non-NULL value from its list of expressions, making it perfect for substituting a default when a value is NULL. For example, COALESCE(email, 'no-email@domain.com') yields the actual email when present, and a fallback string when the email is NULL. This behavior is equivalent to a CASE expression that picks the first non-NULL item. The other operations do different tasks: TRIM removes extra whitespace from strings, not NULLs; concatenating strings joins them together regardless of NULL handling; CAST changes a value’s data type rather than substituting NULLs.

COALESCE returns the first non-NULL value from its list of expressions, making it perfect for substituting a default when a value is NULL. For example, COALESCE(email, 'no-email@domain.com') yields the actual email when present, and a fallback string when the email is NULL. This behavior is equivalent to a CASE expression that picks the first non-NULL item.

The other operations do different tasks: TRIM removes extra whitespace from strings, not NULLs; concatenating strings joins them together regardless of NULL handling; CAST changes a value’s data type rather than substituting NULLs.