NullSupported (Property)

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NullSupported (Property)

In french: NullSupporté

Available only with these kinds of connection

..NullSupported is used to manage the NULL value in HFSQL data files.

This property is used to:

Find out the management mode of the NULL value for a data file described in the data model editor.
Define that the NULL value will be managed when a data file is described by programming.

Remark: If a data file supports the NULL value and if the item allows the management of NULL (..NullAllowed), you will have the ability to use ..Null to assign NULL to the item for the current record for example.

Versions 17 and later

This property is now available for iPhone/iPad applications.

New in version 17

This property is now available for iPhone/iPad applications.

Versions 18 and later

This property is now available in Windows Store Apps mode.

New in version 18

This property is now available in Windows Store Apps mode.

Remark: From version 19, HFSQL is the new name of HyperFileSQL.

Versions 21 and later

This property is now available in Universal Windows 10 App mode.

New in version 21

This property is now available in Universal Windows 10 App mode.

Example

// Define the management mode of the NULL value in the Customer data file
Customer..NullSupported = True

Syntax

Finding out whether the data file supports the management of the NULL value Hide the details

<Result> = <Data file>..NullSupported

<Result>: Boolean

True if the file supports the management of the NULL value,
False otherwise.

<Data file>: Character string (with or without quotes)

Logical name of data file used. This name was defined in the data model editor or by the File description type.

Defining the management mode of the NULL value Hide the details

<Data file>..NullSupported = <Management mode>

<Data file>: Character string (with or without quotes)

Logical name of data file used. This name was defined by the File description type.

<Management mode>: Boolean

True to manage the NULL value,
False otherwise.

Remarks

Special case: View and query

..NullSupported used on a view or query returns True if at least one of the source files supports the NULL value.

Error cases

Write access to ..Null fails if ..NullSupported 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.