The AllowNulls property exposes the ability of a data type to accept NULL as a value.
object.AllowNulls [= value]
object
Expression that evaluates to an object in the Applies To list
value
TRUE or FALSE
Boolean
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.