- Locking records
- Error cases
- Handling records during a transaction
- Transactions and independent HFSQL context
- OLE DB and Native Connectors
<Connection variable>.TransactionStart (Function) In french: <Variable Connexion>.TransactionDébut
 Not available with this kind of connection
Starts a transaction on the data files (HFSQL or accessed via a Native Connector) and creates the transaction file. What information is saved in the transaction file? Whenever a WLanguage function modifies a data file or an index file during a transaction, the former values of the record and the operation performed are stored in the transaction file.
MyConnection1 is Connection
// Start transaction on data files associated with MyConnection1
MyConnection1.TransactionStart()
// Code used to prepare the order to added
// ...
WHEN EXCEPTION IN
// Add the order
Order.Add()
// Validate the addition
MyConnection1.TransactionEnd()
DO
// Delete the order lines
MyConnection1.TransactionCancel()
END
Syntax
Starting a Client/Server transaction on a specific connection Hide the details
<Result> = <Connection>.TransactionStart([<List of data files>])
<Result>: Boolean - True if the transaction was started,
- False if a problem occurs. HErrorInfo returns more details about the error.
<Connection>: Connection variable Name of the Connection variable that describes the connection to use. <List of data files>: Optional character string List of logical names of one or more data files to take into account (or not) in the transaction (in this case, the data file name is preceded by the "-" sign). | | | If this parameter is not specified | All data files used during the transaction will be taken into account in the transaction. | If all data files are prefixed with the "-" sign
For example: "-Customer, -Product" | All data files specified in the list and used during the transaction will not be taken into account by the transaction.
All data files not specified in the list will be taken into account and used during the transaction. | If no data file on the list is prefixed with the "-" sign
For example: "Customer, Product" | All data files specified in the list and used during the transaction will be taken into account in the transaction.
All data files not specified and manipulated during the transaction will be ignored in the transaction. | If some data files are prefixed with "-" and others are not
For example: "-Customer, Product" (equivalent to "Product") | All data files in the list prefixed with "-" and used during the transaction will be ignored in the transaction.
All data files in the list not prefixed with "-" and used during the transaction will be taken into account in the transaction.
The files not specified in the list will be excluded from the transaction. |
Starting a Client/Server transaction on a specific connection Hide the details
<Result> = <Connection>.TransactionStart(<Transaction file> , <List of data files>)
<Result>: Boolean - True if the transaction was started,
- False if a problem occurs. HErrorInfo returns more details about the error.
<Connection>: Connection variable Name of the Connection variable that describes the connection to use. <Transaction file>: Character string Full name of the transaction file (used to store the operations performed within the transaction). This parameter is not taken into account for connections to an HFSQL Server. <List of data files>: Character string List of logical names of one or more data files to take into account (or not) in the transaction (in this case, the data file name is preceded by the "-" sign). | | | If this parameter is not specified | All data files used during the transaction will be taken into account in the transaction. | If all data files are prefixed with the "-" sign
For example: "-Customer, -Product" | All data files specified in the list and used during the transaction will not be taken into account by the transaction.
All data files not specified in the list will be taken into account and used during the transaction. | If no data file on the list is prefixed with the "-" sign
For example: "Customer, Product" | All data files specified in the list and used during the transaction will be taken into account in the transaction.
All data files not specified and manipulated during the transaction will be ignored in the transaction. | If some data files are prefixed with "-" and others are not
For example: "-Customer, Product" (equivalent to "Product") | All data files in the list prefixed with "-" and used during the transaction will be ignored in the transaction.
All data files in the list not prefixed with "-" and used during the transaction will be taken into account in the transaction.
Data files not specified in the list will be excluded from the transaction. |
Remarks Locking records The added, modified or deleted records in a transaction are locked in write mode. Error cases - Nesting transactions: Transactions cannot be nested (i.e. <Connection variable>.TransactionStart cannot be called in a transaction). In this case, error 70031 occurs.
- A fatal error is displayed in the following cases:
- A transaction is started on all the connections while there is at least one connection in transaction.
- A transaction is started on a connection while a transaction was already started on all the connections.
- A transaction is started on all the connections while there is at least one connection whose isolation mode is not "Read Uncommitted".
Handling records during a transaction Transactions and independent HFSQL context When copying a context, if a transaction is in progress on the first context, the new context is not in transaction. You must call <Connection variable>.TransactionStart to start a transaction in the new context.
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