property is used to manage the NULL value in HFSQL data files.
This property is used to:
- Determine how the NULL value is handled for a data file described in the data model editor.
- Define that the NULL value will be handled when a data file is described through programming.
: If the data file and the item support NULL values (NullAllowed
property), the Null
property can be used to assign NULL to the item for the current record.
// Define the management mode of the NULL value in the Customer data file
Customer.NullSupported = True
Determining if the data supports the NULL value Hide the details
<Result> = <Data file>.NullSupported
- True if the file supports the 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.
Special case: View and query
When used on a view or query, the NullSupported property returns True if at least one of the source files supports the NULL value.
Write access to the Null
property fails if the NullSupported
property is set to False
The error 70409 ("You have called HModify
. The <XXXX> file does not support the access to the Null property. The management of the Null value must be enabled in the file description.") occurs if the following conditions are fullfilled:
- an item found in a query or in a view is set to NULL,
- this item comes from a file that does not support the NULL value
- HModify is used on the query or on the view.