Delete Method

Overview

The Delete method marks a row as Deleted but does not remove it from the table. The Delete method behaves differently depending on the current state of the specified row.

If the current state of the row is Deleted or Detached then Delete method does nothing.

If the current state of the row is Added, then the Delete method throws an exception because deleting an added row means it must be removed from the table it was added to, but that action can be done at table level only.

If the current state of the row is Unchanged or Modified then the Delete method changes the row's state to Deleted.

When Delete is called on a row in the Unchanged or Modified state, the framework creates a snapshot of the row’s original values (if one does not already exist). This snapshot allows the deletion to be reverted later by calling RejectChanges.

Important notes:

• Delete is a logical operation and does not immediately remove the row.
• Physical removal of deleted rows occurs only when changes are accepted at the table level.
• Deleted rows can be restored by calling RejectChanges.

Namespace and Assembly

Namespace: PocoDataSet.Data
Assembly: PocoDataSet.Data.dll

Usage Example

Row in the "Unchanged" state:

// 1. Create an empty data set
IDataSet dataSet = DataSetFactory.CreateDataSet();

// 2. Create an empty data table
IDataTable departmentDataTable = dataSet.AddNewTable("Department");
departmentDataTable.AddColumn("Id", DataTypeNames.INT32);
departmentDataTable.AddColumn("Name", DataTypeNames.STRING);

// 3. Create a new row by AddNewRow method on data table, the row state is Added
IDataRow departmentDataRow = departmentDataTable.AddNewRow();
departmentDataRow["Name"] = "Emergency";

// 4. Call the AcceptChanges method to set row state into Unchanged
departmentDataRow.AcceptChanges();

// 5. Call Delete method to mark row as Deleted but not to remove it from table
departmentDataRow.Delete();

Row in the "Added" state:

// 1. Create an empty data set
IDataSet dataSet = DataSetFactory.CreateDataSet();

// 2. Create an empty data table
IDataTable departmentDataTable = dataSet.AddNewTable("Department");
departmentDataTable.AddColumn("Id", DataTypeNames.INT32);
departmentDataTable.AddColumn("Name", DataTypeNames.STRING);

// 3. Create a new row by AddNewRow method on data table, the row state is Added
IDataRow departmentDataRow = departmentDataTable.AddNewRow();
departmentDataRow["Name"] = "Emergency";

// 4. Call Delete method and observe that an InvalidOperationException is thrown
departmentDataRow.Delete();

Row in the "Modified" state:

// 1. Create an empty data set
IDataSet dataSet = DataSetFactory.CreateDataSet();

// 2. Create an empty data table
IDataTable departmentDataTable = dataSet.AddNewTable("Department");
departmentDataTable.AddColumn("Id", DataTypeNames.INT32);
departmentDataTable.AddColumn("Name", DataTypeNames.STRING);

// 3. Create a new row by AddNewRow method on data table, the row state is Added
IDataRow departmentDataRow = departmentDataTable.AddNewRow();
departmentDataRow["Name"] = "Emergency";

// 4. Call the AcceptChanges method to set row state into Unchanged
departmentDataRow.AcceptChanges();

// 5. Assign a new value to put row into Modified state
departmentDataRow["Name"] = "Reception";

// 6. Call Delete method to logically delete the row (row remains in the table)
departmentDataRow.Delete();

 

Table of Content POCO DataSet API References POCO DataSet Types DataRow Members

 

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Business Process Programming in .Net
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