SQLLock (Function)

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How to lock a table or the query records?
Native ORACLE Access
Native MySQL Access

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SQLLock (Function)

In french: SQLBloque

Available only with this kind of connection

Used to lock:

The entire data table, in read and write mode. This data cannot be accessed by the other computers.
The records selected by the query. This data cannot be accessed by the other computers. This method can be used to update records for example. The query result is not returned.

SQLLock can be used on all Native Accesses (except SQLite and XML) and on some OLE DB providers (according to the capacities of provider and database). This function has no effect for the tables accessed by ODBC drivers.

Example

Req is string
// Début de transaction pour bloquer
SQLTransaction(sqlStart)
// Bloque toute la table
SQLLock("CLIENT", "Table")
// Exécute la requête
Req = "UPDATE CLIENT SET NOMCLIENT = 'DUPOND' WHERE REFCLIENT = 1043"
SQLExec(Req, "REQ1")
// Débloquer le fichier
SQLTransaction(sqlCommit)

ReqBloque, ReqUpdate are strings
// Début de transaction pour bloquer
SQLTransaction(sqlStart)
// Définition de Requête
ReqBloque = "SELECT * FROM CLIENT WHERE REFCLIENT = 1043"
// Bloquer le résultat de la requête SELECT
SQLLock(ReqBloque)
// Définition d'une requête de mise à jour
ReqUpdate = "UPDATE CLIENT SET NOMCLIENT = 'DUPOND' WHERE REFCLIENT = 1043"
// Exécution d'une requête de mise à jour
SQLExec(ReqUpdate, "REQ1")
// Débloquer les enregistrements
SQLTransaction(sqlCommit)

Syntax

Locking an entire data table Hide the details

<Result> = SQLLock(<Table name> , <"Table">)

<Result>: Boolean

True if the lock was performed,
False otherwise.

<Table name>: Character string

Name of data table to lock.

<"Table">: Character string

"Table": Character string used to block an entire data table..

Locking the records selected by a query Hide the details

<Result> = SQLLock(<Query text>)

<Result>: Boolean

True if the lock was performed,
False otherwise.

<Query text>: Character string

Text of query used to select the records to lock.

Remarks

How to lock a table or the query records?

To lock a table (or the query records):

Start a transaction (SQLTransaction associated with the sqlStart constant).
Lock the records (SQLLock).
Warning: if you block the records of a query, the query is executed but the result is not returned.
Unlock the records by ending the transaction (SQLTransaction associated with the sqlEnd constant).

Native ORACLE Access

You have the ability to configure the behavior of SQLLock when the record is locked (infinite wait, immediate lock report, ...). This setting is performed in the options of WDORAINS.

Native MySQL Access

SQLLock and SQLTransaction are used to manage locks and transactions only on "InnoDB" tables.

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