NGWS SDK Documentation  

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DataSetCommand Class

Represents a set of data commands and a database connection which are used to fill the DataSet and update the data source. At any time, the object refers to only a single record within the current data set.

Object
   Component
      DataSetCommand

[Visual Basic]
MustInherit Public Class DataSetCommand
   Inherits Component
   Implements ICloneable, IDataSetCommand
[C#]
public abstract class DataSetCommand : Component, ICloneable,
   IDataSetCommand
[C++]
public __gc __abstract class DataSetCommand : public Component,
   ICloneable, IDataSetCommand
[JScript]
public abstract class DataSetCommand extends Component, ICloneable,
   IDataSetCommand

Remarks

In the past, data processing has been primarily connection-based. Now, in an effort to make multi-tiered applications more efficient, data processing is turning to a message-based approach that revolves around selections of information. At the center of this approach is the DataSetCommand, which provides a bridge to retrieve and save data between a DataSet and its source data store. The DataSetCommand provides this bridge by mapping FillDataSet, which changes the data in the DataSet to match the data in the data source, and Update, which changes the data in the data source to match the data in the DataSet.

If you are connecting to a Microsoft SQL Server database, you may wish to increase your overall performance by using the SQLDataSetCommand along with its associated SQLCommand and SQLConnection. For all other OLEDB-supported databases, it is probably better that you use DataSetCommand along with its associated DBCommand and ADOConnection.

When an instance of DataSetCommand is created, the read/write properties are set to initial values. For a list of these values, see the DataSetCommand constructor.

Requirements

Namespace: System.Data.Internal

Assembly: System.Data.dll

Example [C#]

The following example uses the derived classes ADODataSetCommand and SQLDataSetCommand to select records from an Access data source and insert them in a SQL Server data source. This example can be modified to migrate an Access database to a SQL Server database.

[C#]

private DataSet InitializeMyDataSet() {
   // creates the table and its columns for the DataSet
   DataSet newData = new DataSet();
   DataTable newTable = newData.Tables.Add("Catagories");

   // add Columns to table
   newTable.Columns.Add("CategoryID",typeof(Int32));
   newTable.Columns.Add("CategoryName", typeof(String));
   newTable.Columns.Add("Description", typeof(String));
   newTable.Columns.Add("Picture",typeof(Byte[]));
   return newData;
}

public void AccessToSQLServer() {
   // set Access connection and select strings
   const string strAccessConn = "Provider=Microsoft.Jet.OLEDB.4.0;Data Source=NWIND_RW.MDB";
   const string strAccessSelect = "SELECT * FROM Categories ORDER BY CategoryID";
   // set SQL Server connection and insert strings
   const string strSQLServerConn = "Data Source=VBsql7;Initial Catalog=Northwind;User ID=sa;Password=;";
   const string strSQLServerInsert = "INSERT INTO Categories(CategoryName, Description, Picture) Values(@CategoryName,@Description,@Picture)";
   // create my DataSet
   DataSet myDataSet = InitializeMyDataSet();
   // create my Access objects
   ADOConnection myAccessConn = new ADOConnection(strAccessConn);
   ADODataSetCommand myAccessDataSetCmd = new ADODataSetCommand();
   myAccessDataSetCmd.SelectCommand = new ADOCommand(strAccessSelect,myAccessConn);
   // create my SQL Server objects
   SQLConnection mySQLConn = new SQLConnection(strSQLServerConn);
   SQLDataSetCommand mySQLDataSetCmd = new SQLDataSetCommand();
   mySQLDataSetCmd.InsertCommand = new SQLCommand(strSQLServerInsert,mySQLConn);
   // fill myDataSet with data from Access
   myAccessConn.Open();
   try {
      myAccessDataSetCmd.FillDataSet(myDataSet,"table");
   }
   finally {
      myAccessConn.Close();
   }

   // do ugly work to turn original rows into new rows

   // update SQL Server with data from the DataSet
   mySQLConn.Open();
   try {
      mySQLDataSetCmd.InsertCommand.Parameters.Add("CategoryName", typeof(String));
      mySQLDataSetCmd.InsertCommand.Parameters.Add("Description", typeof(String));
      mySQLDataSetCmd.InsertCommand.Parameters.Add("Picture", typeof(Byte[]));
      mySQLDataSetCmd.InsertCommand.Parameters[0].SourceColumn = "CategoryName";
      mySQLDataSetCmd.InsertCommand.Parameters[1].SourceColumn = "Description";
      mySQLDataSetCmd.InsertCommand.Parameters[2].SourceColumn = "Picture";
      mySQLDataSetCmd.Update(myDataSet,"table");
   }
   finally {
      mySQLConn.Close();
   }
}

See Also

DataSetCommand Members | System.Data.Internal Namespace