- Generic search/Exact-match search
- Performing a search on a composite key
- Search on an array item
- Search and filter
- Locks
HSeekFirst (Function) In french: HRecherchePremier
 Not available with this kind of connection
Positions on the first file record whose value for a specific item is greater than or equal to a sought value. The record is not read. The number of the current record is modified when it is returned by HRecNum. For the functions that handle the current record number ( HDelete, HRead, HModify, ...), the value of this number is not updated: you must use HRecNum. Example not to do:
// Deletes a record not corresponding to the expected one
HSeekFirst(Customer, CustomerID, 25)
HDelete(Customer)
to do:
// Delete the sought record
HSeekFirst(Customer, CustomerID, 25)
HDelete(Customer, HRecNum())
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, HSeekFirst is used to position in the data file in order to perform a browse loop among the records corresponding to a condition. Several cases may occur after the call to HSeekFirst: - a record corresponding to the condition was found, locked (if necessary) and loaded in memory: HFound returns True.
- the data file is empty or there is no record corresponding to the condition: HOut returns True.
- 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 only performed on HFSQL Client/Server data files or data files handled by a native access. A HFSQL Mobile record cannot be locked. Indeed, the operating system of Pocket PC does not allow you to lock records.
 Versions 15 and later New in version 15Versions 17 and later New in version 17 Versions 18 and later New in version 18 Note: From version 19, HFSQL is the new name of HyperFileSQL. Versions 21 and later New in version 21
// Find the first record for which
// the CUSTOMER name is MOORE
HSeekFirst(CUSTOMER, NAME, "MOORE")
// The record is not read.
// Finds all the customers with a specific last and first names.
// The search is performed according to a composite key.
bufSoughtVal is Buffer = HBuildKeyValue(CUSTOMER, LASTNAME_FIRSTNAME, sLastName, sFirstName)
HReadSeek(CUSTOMER, LASTNAME_FIRSTNAME, bufSoughtVal, hLockWrite)
WHILE HFound(CUSTOMER) = True
HDelete(CUSTOMER, HRecNum())
HNext(CUSTOMER, LASTNAME_FIRSTNAME, hLockWrite)
END
Syntax
<Result> = HSeekFirst(<File name> , <Name of key item> , <Sought value> [, <Options>])
<Result>: Boolean - True if the positioning was performed (corresponds to the value of HFound).
- False if a problem occurred. This problem can be caused by:
- a positioning problem (empty data file, etc.): HFound returns False and HError returns 0.
- an error: HError returns an integer other than 0. HErrorInfo returns more details.
<File name>: Character string (with or without quotes) Name of HFSQL data file used. <Name of key item>: Character string (with or without quotes) Name of key item on which the search will be performed. <Sought value>: Type corresponding to the value Value of sought item. <Options>: Optional constant (or combination of constants) Configures:- the lock mode applied to the sought record
- the type of search performed.
| | | hLockReadWrite | Lock in read/write: the record currently read cannot be read or modified by another application.
| | hLockWrite | Lock in write mode: the record currently read can be read by another application but it cannot be modified by another application. | | hLockNo | No lock (even if HStartLock was called): the record can be read or modified by another application during the reading. | | hGeneric | Generic search (see the Notes)
An exact-match search is performed by default (constant not specified). | | hLimitParsing | The browse will stop as soon as the last sought value is found. The current record will correspond to this last record found.
HFound will return False and HOut will return True.
This constant is used to optimize the search speed in Client/Server mode. | | hKeepFilter | The filter implemented by HFilter will be taken into account, even if the search key is not optimized for the filter. Reminder: HFilter returns the search key optimized for the filter.
Caution: in this case, lack of performance may occur on the huge files.
By default, the browse operation performed after HSeekFirst ignores the filter. |
Remarks Generic search/Exact-match search - Generic search (mainly on the Character String items): Finds all the records starting with the specified value.
For example: When a generic search is performed on "Martin" (for the NAME item), all records whose Name item starts with "Martin" will correspond to the search. Therefore, the record containing "Martinez" will correspond to the search (HFound returns True). - Exact-match search: Finds all the records that exactly correspond to the specified value.
For example: When an exact-match search is performed on "Smith" (for the NAME item), HFound returns True for the records whose item exactly matches "Smith". - Examples of searches performed on CUSTOMER file sorted by name:
| | | | | | | Sought value | Options | HSeekFirst positions on the record | HFound returns | HOut returns | Explanations | | Durand | | 1 | True | False | Durand exists.
The end of data file was not reached yet. | | Dupuis | | 1 | False | False | Dupuis does not exist. Positioning on the first greater value (Durand).
The end of data file was not reached yet. | | Dupon | hGeneric | 8 | True | False | Dupon does not exist but the search is a generic search and Dupond is found (among other ones).
The end of data file was not reached yet. | | Dupon | | The record was not found (no move) | False | False | Dupon does not exist.
The end of data file was not reached yet. | | Norbert | | The record was not found (no move) | False | True | Norbert does not exist.
Position on the first greater value (this value does not exist): The end of data file has been reached. |
The search is performed on the first array element (element whose subscript is 1). To perform a search on the other array elements, use the filters or queries. If a filter is enabled ( HFilter), this filter is taken into account during the search.
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