Sets the position on the previous record of the data file according to a browse item.
The record is not read .
The number of the current record is modified only when it is returned by
HRecNum . For functions handling the current record number by default (functions
HDelete ,
HRead ,
HModify , ...), the value of this number is not updated: you must use the
HRecNum () function. For example: do not:
but
HDelete ( Client , HRecNum ( ) )
Values in the browse item are read in descending order (for more details, see
the remarks ).
Attention : Record loaded into memory is not modified . The HFSQL variables (for example Customer.Name, i.e. the Name item of the Customer file) are not updated.
Generally, HPrevious sets the position in the data file during a loop operation.
Several cases may occur after the call to HPrevious :
the data file is empty or there is no record corresponding to the filter (defined by HFilter ): function HOut returns True . the function attempts to block a record already blocked in play mode: function HErrorLock returns True and function HOut returns True . JDBC access: lock management is not supported for databases that are accessed through JDBC. HLast ( Client , Nom )
WHILE HOut ( ) = False
HPrevious ( Client , Nom )
END
Syntax
<Result> = HPrevious([<Data file> [, <Search key item>] [, <Options>]])
<Result>: Boolean
True if the position was set,False if an error occurs. This problem can be caused by:or a positioning problem (empty data file, etc.): function HFound returns False and HError returns 0. an error: HError returns an integer other than 0. HErrorInfo returns more details. <Data file>: Optional character string
Name of the HFSQL data file used. If this parameter corresponds to an empty string, HPrevious will use the last data file used by the last HFSQL management function (function starting with "H"). <Search key item>: Optional character string
Name of the key item used to loop through the data file. If this name is not specified, HPrevious will use the last browse item used on this file by the last HFSQL management function (function starting with "H"). If this item does not exist, the best browse item is automatically used. <Options>: Optional constant
Configures the lock and the management of duplicates performed on the record selected by HPrevious :hDistinct If there are any duplicates, sets the position on a single record of the duplicates. This parameter is taken into account only if the iteration is performed on a key item. By default, all duplicates are iterated over. hLockNo No blocking: the Record can be played back or modified by another application. hLockReadWrite Lock in read/write mode: the selected record cannot be read or modified by another application. hLockWrite Lock in write mode: the selected record can be read by another application, but cannot be modified by another application.
Remarks
Read operation based on a key
HPrevious sets the position on the record with the greatest key value.
The sort order taken into account is the one specified in the analysis for this key.
Comparison between HPrevious and HReadPrevious
The function
HPrevious function does not play the Record: the
HPrevious is therefore faster than function
HReadPrevious .