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  • Generic search/Exact-match search
  • Search performed on a key item or on a non-key item
  • Performing a search on a composite key
  • Search on an array item
  • Search and filter
  • Browsing the records corresponding to a condition
  • Exact-match search in Access
  • Locks
  • Optimizing the browse operations
  • Native XML Connector
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WINDEV Mobile
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Stored procedures
Positions on the first record of a data file whose value for a specific item is strictly equal to a sought value (exact-match search). The record is read and the corresponding HFSQL variables are updated.
In most cases, <Source>.ReadSeekFirst sets the position in the data file to browse through the records that correspond to a condition. <Source>.ReadNext is used to read the next record corresponding to the condition.
Several cases may occur after the call to <Source>.ReadSeekFirst:
<Source>.ReadSeekFirst can be used with the data files, HFSQL views or queries.
Remark: the search can be canceled by <Source>.CancelSeek.
JavaPHP Special case: management of locks:
  • PHP In PHP, the management of locks is not available.
  • Java In Java, during an access by JDBC, the management of locks is not available for the databases accessed by JDBC.
Versions 15 and later
WINDEV MobileAndroid This function is now available for Android applications.
New in version 15
WINDEV MobileAndroid This function is now available for Android applications.
WINDEV MobileAndroid This function is now available for Android applications.
Versions 17 and later
iPhone/iPad This function is now available for iPhone/iPad applications.
New in version 17
iPhone/iPad This function is now available for iPhone/iPad applications.
iPhone/iPad This function is now available for iPhone/iPad applications.
Versions 18 and later
Android Widget This function is now available in Android widget mode.
Universal Windows 10 App This function is now available in Windows Store apps mode.
New in version 18
Android Widget This function is now available in Android widget mode.
Universal Windows 10 App This function is now available in Windows Store apps mode.
Android Widget This function is now available in Android widget mode.
Universal Windows 10 App This function is now available in Windows Store apps mode.
Remark: From version 19, HFSQL is the new name of HyperFileSQL.
Versions 21 and later
Universal Windows 10 App This function is now available in Universal Windows 10 App mode.
New in version 21
Universal Windows 10 App This function is now available in Universal Windows 10 App mode.
Universal Windows 10 App This function is now available in Universal Windows 10 App mode.
Example
// Recherche du premier enregistrement pour lequel
// le nom du Client est DUPOND
Client.LitRecherchePremier(Nom, "DUPOND")
SI Client.Trouve() = Faux ALORS
Erreur("Client non trouvé")
RETOUR
SINON
// Suite du traitement sur le client DUPOND
FIN
Syntax
<Result> = <Source>.ReadSeekFirst(<Item> , <Sought value> [, <Options>])
<Result>: Boolean
  • True if the record was found (corresponds to the value returned by <Source>.Found).
  • False if a problem occurred. This problem can be caused by:
<Source>: Type corresponding to the specified source
Name of HFSQL data file, view or query used.
<Item>: Character string
Name of item on which the search will be performed. This item can be a search key or not.
Hyper File 5.5 The search can only be performed on a key item.
<Sought value>: Type corresponding to the value
Value of sought item.
<Options>: Optional constant (or combination of constants)
Used to configure:
  • the lock mode applied to the sought record
  • the type of search performed.
hLockReadWriteLock in read/write: the record currently read cannot be read or modified by another application.
The lock mode is ignored if a query is used.
OLE DB Lock in write-only. Operating mode equivalent to the hLockWrite constant.
PHP This constant is not available.
Java Access by JDBC: This constant is not available.
hLockWriteLock in write mode: the record currently read can be read by another application but it cannot be modified by another application.
The lock mode is ignored if a query is used.
PHP This constant is not available.
Java Access by JDBC: This constant is not available.
hLockNoNo lock: the record can be read or modified by another application during the reading.
PHP This constant is not available.
Java Access by JDBC: This constant is not available.
Versions 17 and later
hForwardOnly
New in version 17
hForwardOnly
hForwardOnly
Native Connectors (Native Accesses) This constant can only be used with Native Connectors.
Used to speed up the browse of data during a simple browse that does not use the following features:
  • Reading the previous record.
  • Modifying a record.
  • Saving position.
If one of these features is used, the result may differ from the expected one.
This constant can be used for example during a browse used to fill a memory table.
hGenericGeneric search (see the Notes)
An exact-match search is performed by default (constant not specified).
hLimitParsingThe browse will stop as soon as the last sought value is found or if no value corresponds to the search.
The current record will correspond to this last record found.
<Source>.Found will return False and <Source>.Out will return True.
This constant is used to optimize search speed in Client/Server mode and on external databases (accessed via OLE DB or via Native Connectors).
hKeepFilterThe 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 files.
Hyper File 5.5 This variable cannot be used.
By default, the browse performed after <Source>.ReadSeekFirst ignores the filter.
hNoRefresh
OLE DBNative Connectors (Native Accesses) <Source>.ReadSeekFirst does not refresh the content of the table or query. If possible, the query is not re-run. All the saved positions are stored.
PHP The management of locks is not available.
Java Access by JDBC: The management of locks is not available for databases accessed by JDBC.
OLE DBNative Connectors (Native Accesses) The lock options will have no effect if the locks are not supported by the OLE DB provider or by the Native Connector.
OLE DB The lock mode specified by <Source>.ReadSeekFirst will remain effective during the calls to <Source>.ReadPrevious and <Source>.ReadNext.
To modify the lock mode, you must use:
Remarks

Generic search/Exact-match search

  • Generic search (mainly on the Character String items): Finds all records starting with the specified value.
    For example: When a generic search is performed on "Smith" (for the NAME item), all records whose Name item starts with "Smith" will match the search. Therefore, the record that contains "Smither" will match the search (<Source>.Found returns True).
    Remark: For backward compatibility with WINDEV 5.5, the generic search of an empty string ("") is equivalent to the use of <Source>.ReadFirst.
  • Exact-match search: Finds all records that exactly correspond to the specified value.
    For example: When an exact-match search is performed on "Smith" (for the NAME item), <Source>.Found returns True for the records whose item exactly matches "Smith".
  • Examples of searches on the CUSTOMER data file sorted by name:
Sought valueOptions<Source>.ReadSeekFirst sets the position on the record.<Source>.Found returns<Source>.Out returnsExplanations
Davon1TrueFalseDavon exists.
The end of data file was not reached yet.
Davo1FalseFalseDavo does not exist. Position on the first greater value (Davon).
The end of data file was not reached yet.
MoorhGeneric8TrueFalseMoor does not exist but the search is a generic search and Moore is found (among others).
The end of data file was not reached yet.
MoorThe record was not found (no move, the current record does not change).FalseFalseMoor does not exist.
The end of data file was not reached yet.
NorbertThe record was not found (no move, the current record does not change).FalseTrueNorbert does not exist.
Position on the first greater value (this value does not exist): the end of data file has been reached.

For more details, see the Hyper File 5.5 and 7: How to manage the space characters in the searches? table

Search performed on a key item or on a non-key item

The search can be performed on a key item or a non-key item.
If the search is performed on a key item:
  • the search is fast and the result is sorted.
  • if the browse operation is continued by <Source>.ReadNext, the next records will correspond to the values greater than or equal to the sought value. In this case, <Source>.Out must be checked after each read operation to find out whether the end of the data file has been reached.
If the search is performed on a non-key item:

Performing a search on a composite key

Several methods can be used to perform a search on a composite key:
1. Using a list of values
The following syntax is used to perform a search on a composite key:
HReadSeekFirst(<File Name>, <Name of Composite Key>,
[<Search value of first element of composite key>,
<Search value of first element of composite key>, ...])
Example:
// Recherche de l'enregistrement
Client.LitRecherchePremier(Nom_Prénom, ["MOULIN", "Françoise"])

2. Using <Source>.BuildKeyValue
Example:
bufValRech est un Buffer = Client.ConstruitValClé(Nom_Prénom, sNom, sPrénom)
Client.RecherchePremier(Nom_Prénom, bufValRech)
TANTQUE Client.Trouve()
Client.Supprime()
Client.Suivant(Nom_Prénom)
FIN

3. Using HConvert
To build the value of a composite key without using <Source>.BuildKeyValue, you must:
  • fill the text components on their entire size with Charact(0).
  • convert the numeric components with HConvert.
Example:
MyCompositeKey = Complete(Customer.CustomerLastName, Dimension(Customer.LastName), Charact(0)) + ...
Complete(Customer.FirstName, Dimension(Customer.FirstName), Charact(0))
Hyper File 5.5 To perform generic searches on a composite key, all the components of composite key must be Text components. Otherwise, an exact-match search is performed.

Search on an array item

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.

Search and filter

If a filter is enabled (<Source>.Filter), the filter is taken into account by the search only if the key used is identical.
To take this filter into account in the rest of browse (even if the search key is not optimized for the filter), use the hKeepFilter constant.
Hyper File 5.5 If a filter is enabled, the filter is ignored by the search.

Browsing the records corresponding to a condition

In most cases, <Source>.ReadSeekFirst sets the position in the data file to browse through the records that correspond to a condition. <Source>.ReadNext and <Source>.ReadPrevious are used to read the next and previous records corresponding to the condition.
To ignore the search while going to the next or previous record, use one of the following functions:
WINDEVWEBDEV - Server codeReports and QueriesUser code (UMC)AjaxOLE DBNative Connectors (Native Accesses)

Exact-match search in Access

To perform an exact-match search on an ACCESS database, it is recommended to use NoSpace if there are space characters at the end of the sought value.
WINDEVWEBDEV - Server codeReports and QueriesUniversal Windows 10 AppiPhone/iPadIOS WidgetMac CatalystUser code (UMC)AjaxHFSQLHFSQL Client/ServerHyper File 5.5OLE DBNative Connectors (Native Accesses)

Locks

The locks apply only when a record was found.
By default (no lock mode specified in <Options>), the record is not locked.
If a lock is requested (hLockWrite or hLockReadWrite constant), the record will be read only if this record is not already locked.
Reminder: A locked record can be unlocked by <Source>.UnlockRecNum.
OLE DBNative Connectors (Native Accesses) Lock options will have no effect if the OLE DB provider or Native Connector (also called Native Access) does not support locks.
WINDEVWEBDEV - Server codeReports and QueriesUniversal Windows 10 AppiPhone/iPadIOS WidgetMac CatalystUser code (UMC)AjaxHFSQLHFSQL Client/ServerHyper File 5.5OLE DBNative Connectors (Native Accesses)

Optimizing the browse operations

To improve the first browse times on a data file, use <Source>.Optimize on this data file.
WINDEVWEBDEV - Server codeReports and QueriesUser code (UMC)Native Connectors (Native Accesses)

Native XML Connector

The behavior of <Source>.ReadSeekFirst depends on <Source>.ActivateAutoFilter and <Source>.DeactivateAutoFilter.
<Source>.ActivateAutoFilter is enabled by default.
Therefore, to read the content of XML file, read the content of main file (the parent) then read the content of linked files (the children).
By default, when reading a file, a filter is automatically applied to the linked files in order to only read the records corresponding to the main file.
For example:
The email of this person can be retrieved when browsing the Person file.
To do so, simply set the position on the "Person" file and apply <Source>.ReadSeekFirst to the "Email" file.
In this case, the record read in the "Email" file will correspond to the first email associated with the current record in the "Person" file.
If this mechanism is disabled (<Source>.DeactivateAutoFilter), the record read in the "Email" file will correspond to the first record found in the Email file (and not to the child of the record read in the "Person" file).
Component: wd270hf.dll
Minimum version required
  • Version 25
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