How to: Check for Changed Rows
When changes are made to records in a dataset, information about those changes is stored until you commit them. Changes are committed when calling the AcceptChanges method of a dataset, data table, or calling the Update method of a TableAdapter or data adapter.
Changes are tracked in each data row two ways:
Each data row contains information as to it's RowState (for example, Added, Modified, Deleted, Unchanged).
Each changed data row contains multiple versions of that row (DataRowVersion); the original (before changes), and current (after changes) versions — that you can access. During the period when a change is pending (the time that you can respond to the RowChanging event), a third version — the proposed version— is available as well. For more information, see How to: Get Specific Versions of a DataRow.
Determining If There Are Changed Rows
The HasChanges method of a dataset returns true if changes have been made in the dataset. After determining that changed rows exist, you can call the GetChanges method of a DataSet or DataTable to return a set of changed rows. For more information, see How to: Retrieve Changed Rows.
To determine if any changes have been made to any rows
Call the HasChanges method of a dataset to check for changed rows.
The following example shows how to check the return value from the HasChanges method to detect whether there are any changed rows in a dataset named NorthwindDataset1.
If NorthwindDataSet1.HasChanges() Then ' Changed rows were detected, add appropriate code. Else ' No changed rows were detected, add appropriate code. End Ifif (northwindDataSet1.HasChanges()) { // Changed rows were detected, add appropriate code. } else { // No changed rows were detected, add appropriate code. }
Determining the Type of Changes
You can also check to see what type of changes have been made in a dataset by passing a value from the DataRowState enumeration to the HasChanges method.
To determine what type of changes have been made to a row
Pass a DataRowState value to the HasChanges method.
The following example shows how to check a dataset named NorthwindDataset1 to determine if there have been any new rows added to it:
If NorthwindDataSet1.HasChanges(DataRowState.Added) Then ' New rows have been added to the dataset, add appropriate code. Else ' No new rows have been added to the dataset, add appropriate code. End Ifif (northwindDataSet1.HasChanges(DataRowState.Added)) { // New rows have been added to the dataset, add appropriate code. } else { // No new rows have been added to the dataset, add appropriate code. }
See Also
Concepts
Other Resources
Editing Data in Your Application
Connecting to Data in Visual Studio
Preparing Your Application to Receive Data
Fetching Data into Your Application