HForward (Function)

The destination record is read and loaded in memory: the HFSQL variables are updated (Customer.Name for example, which means the Name item of Customer file).

Several cases may occur after the call to HForward:

no other record exists in the data file: HOut returns True. No read operation is performed.
the function tries to lock a record that is already locked in read-only: HErrorLock returns True and HOut returns True.
The management of locks is performed on the HFSQL Client/Server data files and on the data files handled by native access. A HFSQL Mobile record cannot be locked. Indeed, the operating system of Pocket PC does not allow you to lock records.
The management of locks is not available in PHP.
Access by JDBC: The management of locks is not available for the databases accessed by JDBC.
The management of locks is not available for the SQLite databases.

This function can be used with the HFSQL files, views or queries.

Versions 15 and later

This function is now available for the Android applications.

New in version 15

This function is now available for the Android applications.

Versions 17 and later

This function is now available for the iPhone/iPad applications.

New in version 17

This function is now available for the 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.

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

Example

See additional examples

// Moves to the 2000th record
// of CUSTOMER file according to CUSTNAME key
HReadFirst(CUSTOMER, CUSTNAME)
HForward(CUSTOMER, CUSTNAME, 1999)

// Check the status report of HForward
// Moves to the 2000th record
// of CUSTOMER file according to CUSTNAME key
HReadFirst(CUSTOMER, CUSTNAME)
IF HForward(CUSTOMER, CUSTNAME, 1999, hLockWrite) = False THEN
IF HErrorLock() = True THEN
Info("This record is currently used")
ELSE
Error(HErrorInfo())
END
END

Syntax

<Result> = HForward([<File name>] [, <Item name> [, <Step> [, <Options>]]])

<Result>: Boolean

True if the move was performed in the file,
False if an error occurred (lock, end of file, etc.): the record is not read. HError is used to identify the error.

<File name>: Optional character string (with or without quotes)

Name of data file, view or query used. If this name is not specified, HForward handles the last data file used by the last function for HFSQL management (starting with the letter H).
This parameter corresponds to a file name.

<Item name>: Optional character string (with or without quotes)

Name of item according to which the browse is performed. If this name is not specified, HForward handles the last file item used by the last function for HFSQL management (starting with the letter H).

<Step>: Optional integer

Number of steps forward (which means number of records to browse). By default, <Step> = 1.
<Step> is mandatory if <Item name> was specified.

<Options>: Optional Integer constant (or combination of constants)

Configures:
the lock mode applied to the record read. By default, the lock performed corresponds to the current lock.
hLockNo No lock (even if HStartLock was called): the record can be read or modified by another application during the reading.
hLockWrite Lock in write mode: the record currently read can be read by another application but it cannot be modified by another application.
hLockReadWrite Lock in read/write: the record currently read cannot be read or modified by another application.

Locks are managed only on HFSQL Client/Server data files or on data files handled by a Native Connector. A HFSQL Mobile record cannot be locked. Indeed, the operating system of Pocket PC does not allow you to lock records.
The lock options will have no effect if the locks are not supported by the OLE DB provider or by the Native Connector.
Access by JDBC: The management of locks is not available for the databases accessed by JDBC.
The management of locks is not available for the SQLite databases.
the management of duplicates during the browse. By default, all the duplicates are browsed.
hDistinct When a browse is performed on a key item, a single record is browsed if duplicates are found.
<Options> is ignored.
<Options> is ignored.

Remarks

Read operation according to a key item or not

In all cases, the browse operation must have been initialized by one of the following functions: HReadFirst, HFirst, HReadSeekFirst, HSeekFirst, HChangeKey, HRestorePosition.

If the item used is a key item:

if the hDistinct constant is not specified, HForward moves forward <Step> key values from the current position.
if the hDistinct constant is specified, HForward moves forward <Step> key values from the current position. If duplicates are found, a single duplicate is read.

If the item used is not a key item:

the hDistinct constant is not available.
HForward moves foward from <Step> active records from the current position.

Memos

The memos associated with the record can be automatically read (or not) when reading the record. HSetMemo is used to customize this automatic read operation.

If the memos are supported, the associated text memos are read when the record is read. The binary memos are read only when they are explicitly used (HExtractMemo).

Lock

By default (no lock variable specified), the lock performed corresponds to the current lock mode.

If a lock is specified (hLockWrite or hLockReadWrite constant), the record will be read and locked only if it is not already locked by another application.

There is no need to specify a lock constant if the file is locked by HStartLock: the lock specified by HStartLock is automatically taken into account. To ignore the lock specified by HStartLock, use the hLockNo constant.

The lock options will have no effect if the locks are not supported by the OLE DB provider or by the Native Connector.

Various

The result of HFound must be ignored (HFound must be used for the searches performed by HReadSeek).
The current record number is returned by HRecNum.
HForward respects the current active filter (defined by HFilter).
HChangeKey is used to modify the search key while being positioned on the current record.
HForward(Customer,Name) is equivalent to HReadNext(Customer,Name)

Component : wd240hf.dll