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*nvl

Library: fbudf

Added in: 1.0 (Win), 1.5 (Linux)

Better alternative: Internal function COALESCE()

Description

The four nvl functions – for integers, bigints, doubles and strings, respectively – are NULL replacers. They each return the first argument's value if it is not NULL. If the first argument is NULL, the value of the second argument is returned.

Result type: varies, see declarations.

Syntax

 invl (int1, int2)
 i64nvl (bigint1, bigint2)
 dnvl (double1, double2)
 snvl (string1, string2)

As from Firebird 1.5, use of the internal function COALESCE is preferred.

Warning: i64nvl and dnvl will return wrong and/or bizarre results if it is not absolutely clear to the engine that each argument is of the intended type (NUMERIC(18,0) or DOUBLE PRECISION). If in doubt, cast both arguments explicitly to the declared type (see declarations below).

Declarations

 DECLARE EXTERNAL FUNCTION invl
   INT BY DESCRIPTOR, INT BY DESCRIPTOR
   RETURNS INT BY DESCRIPTOR
   ENTRY_POINT 'idNvl' MODULE_NAME 'fbudf'

 DECLARE EXTERNAL FUNCTION i64nvl
   NUMERIC(18,0) BY DESCRIPTOR, NUMERIC(18,0) BY DESCRIPTOR
   RETURNS NUMERIC(18,0) BY DESCRIPTOR
   ENTRY_POINT 'idNvl' MODULE_NAME 'fbudf'

 DECLARE EXTERNAL FUNCTION dnvl
   DOUBLE PRECISION BY DESCRIPTOR, DOUBLE PRECISION BY DESCRIPTOR
   RETURNS DOUBLE PRECISION BY DESCRIPTOR
   ENTRY_POINT 'idNvl' MODULE_NAME 'fbudf'

 DECLARE EXTERNAL FUNCTION snvl
   VARCHAR(100) BY DESCRIPTOR, VARCHAR(100) BY DESCRIPTOR,
   VARCHAR(100) BY DESCRIPTOR RETURNS PARAMETER 3
   ENTRY_POINT 'sNvl' MODULE_NAME 'fbudf'

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