Chapter 1: System and User-Defined Datatypes

Automatic conversion of fixed-length NULL columns

Only columns with variable-length datatypes can store null values. When you create a NULL column with a fixed-length datatype, Adaptive Server automatically converts it to the corresponding variable-length datatype. Adaptive Server does not inform the user of the datatype change.

Table 1-4 lists the fixed- and variable-length datatypes to which they are converted. Certain variable-length datatypes, such as moneyn, are reserved datatypes; you cannot use them to create columns, variables, or parameters:

**Table 1-4: Automatic conversion of fixed-length datatypes**
Original fixed-length datatype	Converted to
char	varchar
unichar	univarchar
nchar	nvarchar
binary	varbinary
datetime	datetimn
date	daten
time	timen
float	floatn
bigint, int, smallint, and tinyint	intn
unsigned bigint, unsigned int, and unsigned smallint	uintn
decimal	decimaln
numeric	numericn
money and smallmoney	moneyn

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