MySQL IFNULL() to PostgreSQL COALESCE() Crosswalk

PostgreSQL's COALESCE() covers everything MySQL's IFNULL() does for the common 2-argument case, and goes further by accepting any number of fallback expressions.

Close equivalent Covers the common case, but has documented behavioral differences.

MySQL feature: IFNULL()
PostgreSQL equivalent: COALESCE()

Main limitation: IFNULL() takes exactly two arguments; COALESCE() accepts any number and returns the first non-null one. For a straight 2-argument port they behave identically, but COALESCE's variadic form lets you flatten nested IFNULL() calls into one expression.

Quick mapping

MySQL	`IFNULL()`
PostgreSQL	`COALESCE()`

Examples

Fallback for a NULL column value

SELECT IFNULL(nickname, username) AS display_name FROM users;

SELECT COALESCE(nickname, username) AS display_name FROM users;

A direct, exact port for the common 2-argument case.

Chaining multiple fallbacks

SELECT IFNULL(nickname, IFNULL(username, 'Anonymous')) FROM users;

SELECT COALESCE(nickname, username, 'Anonymous') FROM users;

COALESCE's variadic signature replaces nested IFNULL() calls with a single, flatter expression.

Caveats

Caveat

IFNULL() takes exactly two arguments; COALESCE() accepts any number and returns the first non-null one. For a straight 2-argument port they behave identically, but COALESCE's variadic form lets you flatten nested IFNULL() calls into one expression.

Caveat

MySQL's IFNULL() determines its result type from the two argument types using MySQL-specific coercion rules; PostgreSQL's COALESCE() requires all arguments to share (or be coercible to) one type up front, so mixing incompatible types errors in PostgreSQL where MySQL might silently convert.

Caveat

COALESCE() is ANSI SQL standard and behaves identically across PostgreSQL, SQL Server, and Oracle; IFNULL() is MySQL-specific — SQL Server's nearest equivalent is ISNULL(), a different name again with only 2-argument support.

References

MySQL Reference Manual — IFNULL() (v8.4) — checked 2026-07-29
PostgreSQL docs — COALESCE (v17) — checked 2026-07-29

Last verified 2026-07-29.