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- Read operation based on a key
- Checking password
- Miscellaneous
- Comparison between .ReadFirst and <Source>.First
- Locks
<Source>.First (Function) In french: <Source>.Premier
Not available with this kind of connection
Sets the position on the first record of a data file according to the specified browse item. The record is not read. The number of the current record is modified only when it is returned by <Source>.RecNum. For functions handling the current record number by default (functions <Source>.Delete, <Source>.Read, <Source>.Modify, ...), the value of this number is not updated: you must use the <Source>.RecNum() function. For example: do not:
but
Customer.Delete(Customer.RecNum())
Values in the browse item are read in ascending order (for more details, see the remarks). Caution: The record loaded into memory is not modified. HFSQL variables (e.g. Client.Name, i.e. the Nom field in the Clientfile) are not updated. In most cases, <Source>.First is used to set the position in the data file in order to perform a read loop with <Source>.Next. Several cases may occur after the call to <Source>.First: - the data file is empty or there is no record corresponding to the filter (defined by function <Source>.Filter): function <Source>.Out returns True.
- the function attempts to block a record already blocked in playback: function HErrorLock returns True and function <Source>.Out returns True.
JDBC access: lock management is not supported for databases that are accessed through JDBC.
Customer.First(Name)
WHILE Customer.Out() = False
Customer.Next(Name)
END
Syntax
<Result> = <Source>.First([<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 <Source>.Found returns Faux and function HError returns 0.
- an error: HError returns an integer other than 0. HErrorInfo returns more details.
<Source>: Type corresponding to the specified source Name of the data file used. <Search key item>: Optional character string Name of the key item used to loop through the data file. If this name is not specified, <Source>.First will use the last browse item used on this data 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 set on the record selected by <Source>.First: | | hKeepFilter | The filter set by <Source>.Filter will be taken into account, even if the search key is not optimized for the filter. Reminder: <Source>.Filter returns the optimized search key for the filter. Caution: In this case, on large data files, performance problems may occur..
| hLockNo | No blocking: the recording 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..
| hNoRefresh | |
Remarks Read operation based on a key <Source>.First positions on the record with the smallest key value. The sort order taken into account is the one specified in the analysis for this key. If duplicates are found, <Source>.First sets the position on the first "duplicate" record according to the sequence of record numbers. Comparison between <Source>.ReadFirst and <Source>.First The function <Source>.First function does not play the recording: the <Source>.First is therefore faster than function <Source>.ReadFirst.
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