HCancelDeclaration (Function)

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Conditions for using HCancelDeclaration

HCancelDeclaration and closing the data file

See also

ExecuteQueryAsynchronous

ExecuteSQLQueryAsynchronous

HCreateMoveableReplica

HCreateSubscriberReplica

HDeactivateAutoFilter

HDescribeFullTextIndex

HErrorStatusModification

HExecuteQuery

HExecuteQueryAsynchronous

HExecuteSQLQuery

HExecuteSQLQueryAsynchronous

HFilterIncludedBetween

HMigrateLinkedCompositeKey

HRecreateSubscriberReplica

This content has been translated automatically. Click here to view the French version.

Conditions for using HCancelDeclaration
HCancelDeclaration and closing the data file

WINDEV

WEBDEV

WINDEV Mobile

Others

See also

HCancelDeclaration (Function)

In french: HAnnuleDéclaration

Not available with this kind of connection

Allows to:

Delete a declaration previously made with HDeclare, HDeclareExternal, HDescribeFile. After this operation, the data file is no longer recognized by the HFSQL engine.
Free the resources of a request (following the use of the HExecuteQuery or HExecuteSQLQuery functions).

Versions 15 and later

This function is now available for Android applications.

New in version 15

This function is now available for Android applications.

Versions 17 and later

This function is now available for iPhone/iPad applications.

New in version 17

This function is now available for iPhone/iPad applications.

Versions 18 and later

This function is now available in Android Widget mode.

This function is now available in Windows Store apps mode.

New in version 18

This function is now available in Android Widget mode.

This function is now available in Windows Store apps mode.

This function is now available in Android Widget mode.

This function is now available in Windows Store apps mode.

Versions 21 and later

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

New in version 21

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

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

Example

See additional examples

// The Customer data file was declared beforehand in the analysis
// by HDeclareExternal
HClose(Customer)
HCancelDeclaration(Customer)

Syntax

<Result> = HCancelDeclaration([<Data file>])

<Result>: Boolean

True if the operation was performed,
False if a problem occurred. HError is used to identify the error.

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

Corresponds to:
the name of data file (defined in the analysis). If this name is not specified, HCancelDeclaration refers to the last data file used.
the name of a query or a data source associated with a query (case of a resource release following the use of the HExecuteQuery or HExecuteSQLQuery functions).

Remarks

Conditions for using HCancelDeclaration

This function must be used ONLY when the relevant data file (or query) is not used anymore!

In the following example, HCancelDeclaration is used too soon: the content of the Table control will be completely distorted. Indeed, BuildBrowsingTable (used to fill the Table control) is run in background task in a parallel process. Therefore, HCancelDeclaration will be called before the table is entirely filled, making this table unusable.

HExecuteSQLQuery("test", "select * from customer")
BuildBrowsingTable(TABLE_Table1, "test")
HCancelDeclaration("test")

Remark: The problem can also occur with a "data source" variable. A "data source" variable declared locally in a process or event (button click, procedure, method, etc.) ONLY exists while this code is run. For this reason, a "warning" is displayed when you are using this type of data source: "the data source will be destroyed at the end of this code".

HCancelDeclaration and closing the data file

To use HCancelDeclaration on a data file, this data file must be closed.

If a query, subquery or view uses the data file, the function HCancelDeclaration cannot be executed even after a call to the HClose function. . The queries or views that are using the data file must be freed beforehand.

Component: wd260hf.dll