Updating data
After users have made changes to data in a DataWindow control,
you can use the Update method to save those changes in the
database.
In PowerBuilder, the code looks like this:
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dw_emp.Update() |
Update sends to the database all inserts, changes, and deletions
made in the DataWindow control since the last Update method. When you
are using an external transaction object, you can then commit (or roll
back) those database updates. In PowerBuilder, you use SQL
statements.
For more specifics on how a DataWindow control updates the
database (that is, which SQL statements are sent in which situations),
see Updating the
database.
Examples
The following example shows code that connects, retrieves,
updates, commits or rolls back, and disconnects from the
database.
Although the example shows all database operations in a single
script or function, most applications separate these operations. In a
PowerBuilder application, for example, an application could connect to
the database in the application Open event, retrieve and update data
in one or more window scripts, and disconnect from the database in the
application Close event.
PowerBuilder
The following statements retrieve and update data using the
transaction object EmpSQL and the DataWindow control dw_emp:
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// Connect to the database specified in the // transaction object EmpSQL CONNECT USING EmpSQL; // Set EmpSQL as the transaction object for dw_emp dw_emp.SetTransObject(EmpSQL) // Retrieve data from the database specified in // EmpSQL into dw_emp dw_emp.Retrieve( ) // Make changes to the data... ... // Update the database IF dw_emp.Update( ) > 0 THEN COMMIT USING EmpSQL; ELSE ROLLBACK USING EmpSQL; END IF // Disconnect from the database DISCONNECT USING EmpSQL; |
Handling retrieval or update
errors
A production application should include error tests after each
database operation. For more about checking for errors, see Handling DataWindow
errors.