---
title: "Using an External Dataset with Reporting Services | Microsoft Docs"
ms.date: 03/06/2017
ms.prod: reporting-services
ms.prod_service: "reporting-services-native"
ms.technology: extensions


ms.topic: reference
helpviewer_keywords: 
  - "DataSet objects [Reporting Services]"
  - "data processing extensions [Reporting Services], custom DataSet objects"
  - "custom DataSet objects [Reporting Services]"
  - "external DataSet objects [Reporting Services]"
ms.assetid: 11daa013-ec17-4760-80e3-6d84cd8d5722
author: maggiesMSFT
ms.author: maggies
---
# Using an External Dataset with Reporting Services
  The **DataSet** object is central to supporting disconnected, distributed data scenarios with [!INCLUDE[vstecado](../../../includes/vstecado-md.md)]. The **DataSet** object is a memory-resident representation of data that provides a consistent relational programming model regardless of the data source. It can be used with multiple different data sources, with XML data, or to manage data local to the application. The **DataSet** object represents a complete set of data, including related tables, constraints, and relationships among the tables. Because of the **DataSet** object's versatility in storing and exposing data, your data may often be processed and transformed into a **DataSet** object before any reporting on that data occurs.  
  
 With [!INCLUDE[ssRSnoversion](../../../includes/ssrsnoversion-md.md)] data processing extensions, you can integrate any custom **DataSet** objects that are created by external applications. To accomplish this, you create a custom data processing extension in [!INCLUDE[ssRSnoversion](../../../includes/ssrsnoversion-md.md)] that acts like a bridge between your **DataSet** object and the report server. Most of the code for processing this **DataSet** object is contained in the **DataReader** class that you create.  
  
 The first step in exposing your **DataSet** object to the report server is to implement a provider specific method in your **DataReader** class that can populate a **DataSet** object. The following example shows how to load static data into a **DataSet** object by using a provider-specific method in your **DataReader** class.  
  
```vb  
'Private members of the DataReader class  
Private m_dataSet As System.Data.DataSet  
Private m_currentRow As Integer  
  
'Method to create a dataset  
Friend Sub CreateDataSet()  
   ' Create a dataset.  
   Dim ds As New System.Data.DataSet("myDataSet")  
   ' Create a data table.   
   Dim dt As New System.Data.DataTable("myTable")  
   ' Create a data column and set various properties.   
   Dim dc As New System.Data.DataColumn()  
   dc.DataType = System.Type.GetType("System.Decimal")  
   dc.AllowDBNull = False  
   dc.Caption = "Number"  
   dc.ColumnName = "Number"  
   dc.DefaultValue = 25  
   ' Add the column to the table.   
   dt.Columns.Add(dc)  
   ' Add 10 rows and set values.   
   Dim dr As System.Data.DataRow  
   Dim i As Integer  
   For i = 0 To 9  
      dr = dt.NewRow()  
      dr("Number") = i + 1  
      ' Be sure to add the new row to the DataRowCollection.   
      dt.Rows.Add(dr)  
   Next i  
  
   ' Fill the dataset.  
   ds.Tables.Add(dt)  
  
   ' Use a private variable to store the dataset in your  
   ' DataReader.  
   m_dataSet = ds  
  
   ' Set the current row to -1.  
   m_currentRow = - 1  
End Sub 'CreateDataSet  
```  
  
```csharp  
// Private members of the DataReader class  
private System.Data.DataSet m_dataSet;  
private int m_currentRow;  
  
// Method to create a dataset  
internal void CreateDataSet()  
{  
   // Create a dataset.  
   System.Data.DataSet ds = new System.Data.DataSet("myDataSet");  
   // Create a data table.   
   System.Data.DataTable dt = new System.Data.DataTable("myTable");  
   // Create a data column and set various properties.   
   System.Data.DataColumn dc = new System.Data.DataColumn();   
   dc.DataType = System.Type.GetType("System.Decimal");   
   dc.AllowDBNull = false;   
   dc.Caption = "Number";   
   dc.ColumnName = "Number";   
   dc.DefaultValue = 25;   
   // Add the column to the table.   
   dt.Columns.Add(dc);   
   // Add 10 rows and set values.   
   System.Data.DataRow dr;   
   for(int i = 0; i < 10; i++)  
   {   
      dr = dt.NewRow();   
      dr["Number"] = i + 1;   
      // Be sure to add the new row to the DataRowCollection.   
      dt.Rows.Add(dr);  
   }  
  
   // Fill the dataset.  
   ds.Tables.Add(dt);  
  
   // Use a private variable to store the dataset in your  
   // DataReader.  
   m_dataSet = ds;  
  
   // Set the current row to -1.  
   m_currentRow = -1;  
}  
```  
  
```csharp  
public bool Read()  
{  
   m_currentRow++;  
   if (m_currentRow >= m_dataSet.Tables[0].Rows.Count)   
   {  
      return (false);  
   }   
   else   
   {  
      return (true);  
   }  
}  
  
public int FieldCount  
{  
   // Return the count of the number of columns, which in  
   // this case is the size of the column metadata  
   // array.  
   get { return m_dataSet.Tables[0].Columns.Count; }  
}  
  
public string GetName(int i)  
{  
   return m_dataSet.Tables[0].Columns[i].ColumnName;  
}  
  
public Type GetFieldType(int i)  
{  
   // Return the actual Type class for the data type.  
   return m_dataSet.Tables[0].Columns[i].DataType;  
}  
  
public Object GetValue(int i)  
{  
   return m_dataSet.Tables[0].Rows[m_currentRow][i];  
}  
  
public int GetOrdinal(string name)  
{  
   // Look for the ordinal of the column with the same name and return it.  
   // Returns -1 if not found.  
   return m_dataSet.Tables[0].Columns[name].Ordinal;  
}  
```  
  
 Once you create or retrieve your dataset, you can use the **DataSet** object in your implementations of the **Read**, **GetValue**, **GetName**, **GetOrdinal**, **GetFieldType**, and **FieldCount** members of the **DataReader** class.  
  
## See Also  
 [Reporting Services Extensions](../../../reporting-services/extensions/reporting-services-extensions.md)   
 [Implementing a Data Processing Extension](../../../reporting-services/extensions/data-processing/implementing-a-data-processing-extension.md)   
 [Reporting Services Extension Library](../../../reporting-services/extensions/reporting-services-extension-library.md)