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 the functions that handle the current record number (
<Source>.Delete,
<Source>.Read,
<Source>.Modify, etc.), the value of this number is not updated: you must use
<Source>.RecNum(). For example: not to do:
but
Customer.Delete(Customer.RecNum())
Values in the browse item are read in ascending order (see Remarks for more details).
Caution: The record loaded in memory is not modified. The HFSQL variables (Customer.Name for example, which means the Name item of Customer file) are not updated.
In most cases,
<Source>.First sets the position in the data file to loop through the records that match a condition.
<Source>.Next is used to position on the next record corresponding to the condition.
Several cases may occur after the call to <Source>.First:
- a record corresponding to the condition was found: <Source>.Found returns True
- the data file is empty or there is no record corresponding to the condition: <Source>.Out returns True
Remarks:
Values in the browse item are read in ascending order (see remarks for more details).
Caution: The record loaded in memory is not modified. The HFSQL variables (Customer.Name for example, which means the Name item of Customer file) 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 no record corresponds to the filter (defined by <Source>.Filter): <Source>.Out returns True.
- the function tries to lock a record that is already locked in read-only: HErrorLock returns True and <Source>.Out returns True.
Access by JDBC: The management of locks is not available for databases accessed by JDBC.
Customer.First(Name)
WHILE Customer.Out() = False
// Process the record
Customer.Next(Name)
END
Syntax
<Result> = <Source>.First([<Search key item> [, <Options>]])
<Result>: Boolean
- True if the position was set,
- False if an error occurred. This problem can be caused by:
<Source>: Type corresponding to the specified source
Name of the data file used.
<Search key item>: Optional character string
Name of 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 search key optimized for the filter.
Caution: In this case, performance issues may arise for large data files.
|
| hLockNo | No lock: the record can be read or modified by another application.
|
| hLockReadWrite | Lock in read/write: 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 it cannot be modified by another application.
|
| hNoRefresh | |
Remarks
Read operation according to a key
<Source>.First positions on the record with the smallest key value.
The sort order is the one that was 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.