AcceptChanges is called. This will raise both the DataTable. RowChanging and DataTable. RowChanged events for the updated DataRow. Each command associated with the DataAdapter usually has a parameters collection associated with it. Parameters are mapped to the current row through the SourceColumn and SourceVersion properties of a. NET data provider's Parameter class. SourceColumn refers to a DataTable column that the DataAdapter references to obtain parameter values for the current row.
SourceColumn refers to the unmapped column name before any table mappings have been applied. If SourceColumn refers to a nonexistent column, the action taken depends on one of the following MissingMappingAction values. An exception is generated if it refers to a nonexistent column.
The SourceVersion property of a. NET data provider's Parameter class determines whether to use the Original, Current, or Proposed version of the column value. If either of these methods are called before the Update method is called, no changes will be committed when the Update method is called, unless further changes have been made since AcceptChanges or AcceptChanges was called.
If an error occurs while updating a row, an exception is thrown and execution of the update is discontinued. To continue the update operation without generating exceptions when an error is encountered, set the ContinueUpdateOnError property to true before calling Update. You may also respond to errors on a per-row basis within the RowUpdated event of a DataAdapter. To continue the update operation without generating an exception within the RowUpdated event, set the Status property of the RowUpdatedEventArgs to Continue.
For every column that you propagate to the data source on Update , a parameter should be added to the InsertCommand , UpdateCommand , or DeleteCommand. The SourceColumn property of the parameter should be set to the name of the column.
We will use it again to show you a simple update in a second. NET has to dedicate less resources to managing the internal record pointer and can speed up access. This means it is great for any situation where you simply want to loop through the values quickly and easily without needing to go back.
Nice for report displays etc. We could reset the pointer, but then that would kill the speed here. Again this is faster than the other methods and you will certainly see a difference when it comes to loading larger lists of data. That is, any SQL that is not a select aka insert, update and delete.
The function above is very simple and straight forward. We simply make a new command object, give it the connection make sure it is open first and an update query for the commandtext. We then call the ExecuteNonQuery method to make the update happen.
If we were to use one of the other methods again to read this database table back to us, we would see that the Access database Employees table would be modified. Again, very simple and straight forward. However, if you are working with Access and only need to do something real quick, this example should serve you well.
NOTE: A word on security here, make sure you always validate the information coming in from the user before using them in any kind of database query. This, along with a nicely setup query string, can help you avoid nasty people injecting bad code into your database.
As always, treat all user input as dirty input! You will quickly be able to build some great applications which utilize databases for your own small projects. For more advanced features, I suggest you take an extra hard look at the command, connection and dataset classes.
These are the building blocks for using databases in. He has been a programmer for over 23 years. He works for a hot application development company in Vancouver Canada which service some of the biggest tech companies in the world.
He has won numerous awards for his mentoring in software development and contributes regularly to several communities around the web. He is an expert in numerous languages including. Related Posts 10 Reasons to switch from Java to C? Next Post ». The OnRowUpdated event is raised. AcceptChanges is called. Each command associated with the DbDataAdapter usually has a parameters collection associated with it. Parameters are mapped to the current row through the SourceColumn and SourceVersion properties of a.
NET Framework data provider's Parameter class. SourceColumn refers to a DataTable column that the DbDataAdapter references to obtain parameter values for the current row. SourceColumn refers to the unmapped column name before any table mappings have been applied.
If SourceColumn refers to a nonexistent column, the action taken depends on one of the following MissingMappingAction values. An exception is generated if it refers to a nonexistent column. The SourceVersion property of a. NET Framework data provider's Parameter class determines whether to use the Original, Current, or Proposed version of the column value.
If an error occurs while updating a row, an exception is thrown and execution of the update is discontinued. To continue the update operation without generating exceptions when an error is encountered, set the ContinueUpdateOnError property to true before calling Update. You may also respond to errors on a per-row basis within the RowUpdated event of a DataAdapter. To continue the update operation without generating an exception within the RowUpdated event, set the Status property of the RowUpdatedEventArgs to Continue.
An array of DataRow objects used to update the data source. The TableMappings collection to use. The number of rows successfully updated from the array of DataRow objects.
No DataRow exists to update. No DataTable exists to update. No DataSet exists to use as a source. The DataTable used to update the data source. The number of rows successfully updated from the DataTable.
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