This feature will be removed in a future version of Microsoft SQL Server. Avoid using this feature in new development work, and plan to modify applications that currently use this feature.
The AllowNulls property exposes the ability of a data type to accept NULL as a value.
An expression that evaluates to an object in the Applies To list
TRUE or FALSE
Read-only for SystemDatatype objects. Read/write for Column and UserDefinedDatatype objects.
HRESULT GetAllowNulls(LPBOOL pRetVal);
HRESULT SetAllowNulls(BOOL NewValue);
If TRUE, the Microsoft SQL Server data type or column referenced can accept NULL as a value.
If FALSE, NULL is not allowed.
Set the AllowNulls property to set NULL as an accepted value for columns and user-defined data types.