Using the COALESCE Function

• The advantage of the COALESCE function over the NVL function is that the COALESCE function can take multiple alternate values.

• If the first expression is not null, it returns that expression; otherwise, it does a COALESCE of the remaining expressions.


The COALESCE Function.

The COALESCE function returns the first non-null expression in the list.

Syntax
COALESCE (expr1, expr2, ... exprn)


In the syntax:

expr1 returns this expression if it is not null
expr2 returns this expression if the first expression is null and this expression is not null exprn returns this expression if the preceding expressions are null