¿Error en COALESCE?

[Casimiro Noteví]

Substituting NULL with a value
The COALESCE function

The COALESCE function in Firebird 1.5 and higher can convert NULL to most anything else. This enables you to perform an on-the-fly conversion and use the result in your further processing, without the need for “if (MyExpression is null) then” or similar constructions. The function signature is:

COALESCE( Expr1, Expr2, Expr3, ... )

COALESCE returns the value of the first non-NULL expression in the argument list. If all the expressions are NULL, it returns NULL.

https://www.firebirdsql.org/manual/n...nversions.html