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
float	floatn
int, smallint, and tinyint	intn
decimal	decimaln
numeric	numericn
money and smallmoney	moneyn