property is used to manage the NULL value in items of HFSQL data files or in items of data files accessed via Native Connectors.
This property is used to:
- Assign NULL to the item for the current record.
- Find out whether the item is associated with the NULL value for the current record.
- Define the default value of an item when the item is described through programming.
// Assign NULL to the Customer.CellPhone item
Customer.CellPhone.Null = True
Finding out whether the item is associated with the NULL value Hide the details
<Result> = <Data file>.<Item>.Null
- True if the item associated with the current record has a NULL value,
- False otherwise.
<Data file>: Character string
Logical name of the data file used. This name was defined in the data model editor or with the File Description type.
<Item>: Character string
Name of the item used.
How to know whether a data file supports the management of NULL value?
- To determine if a data file allows the use of the NULL value, use the NullSupported property.
- To determine if am item allows the use of the NULL value, use the NullAllowed property.
- It is not possible to assign a value to the Null property on a data file or item that does not support the NULL value: a fatal error occurs.
- Reading the Null property on a data file or item that does not support the NULL value always returns False.
- The NULL value cannot be used:
- on the array items.
- on the automatic identifiers.
- on the composite keys.
- The NULL value cannot be assigned several times to an item that takes the management of duplicates into account.