GetSchema and Schema Collections

The Connection classes in each of the .NET Framework managed providers implement a GetSchema method which is used to retrieve schema information about the database that is currently connected, and the schema information returned from the GetSchema method comes in the form of a DataTable. The GetSchema method is an overloaded method that provides optional parameters for specifying the schema collection to return, and restricting the amount of information returned.

Specifying the Schema Collections

The first optional parameter of the GetSchema method is the collection name which is specified as a string. There are two types of schema collections: common schema collections that are common to all providers, and specific schema collections which are specific to each provider.

You can query a .NET Framework managed provider to determine the list of supported schema collections by calling the GetSchema method with no arguments, or with the schema collection name "MetaDataCollections". This will return a DataTable with a list of the supported schema collections, the number of restrictions that they each support, and the number of identifier parts that they use.

Retrieving Schema Collections Example

The following examples demonstrate how to use the GetSchema method of the .NET Framework Data Provider for the SQL Server SqlConnection class to retrieve schema information about all of the tables contained in the AdventureWorks sample database:

Imports System.Data.SqlClient  

Module Module1  
   Sub Main()  
      Dim connectionString As String = GetConnectionString()  
      Using connection As New SqlConnection(connectionString)  
         'Connect to the database then retrieve the schema information.  
         connection.Open()  
         Dim table As DataTable = connection.GetSchema("Tables")  

         ' Display the contents of the table.  
         DisplayData(table)  
         Console.WriteLine("Press any key to continue.")  
         Console.ReadKey()  
      End Using  
   End Sub  

   Private Function GetConnectionString() As String  
      ' To avoid storing the connection string in your code,    
      ' you can retrieve it from a configuration file.  
      Return "Data Source=(local);Database=AdventureWorks;" _  
         & "Integrated Security=true;"  
   End Function  

   Private Sub DisplayData(ByVal table As DataTable)  
      For Each row As DataRow In table.Rows  
         For Each col As DataColumn In table.Columns  
            Console.WriteLine("{0} = {1}", col.ColumnName, row(col))  
         Next  
         Console.WriteLine("============================")  
      Next  
   End Sub  
End Module  
using System;  
using System.Data;  
using System.Data.SqlClient;  

class Program  
{  
  static void Main()  
  {  
  string connectionString = GetConnectionString();  
  using (SqlConnection connection = new SqlConnection(connectionString))  
  {  
   // Connect to the database then retrieve the schema information.  
   connection.Open();  
   DataTable table = connection.GetSchema("Tables");  

   // Display the contents of the table.  
   DisplayData(table);  
   Console.WriteLine("Press any key to continue.");  
   Console.ReadKey();  
   }  
 }  

  private static string GetConnectionString()  
  {  
   // To avoid storing the connection string in your code,  
   // you can retrieve it from a configuration file.  
   return "Data Source=(local);Database=AdventureWorks;" +  
      "Integrated Security=true;";  
  }  

  private static void DisplayData(System.Data.DataTable table)  
  {  
     foreach (System.Data.DataRow row in table.Rows)  
     {  
        foreach (System.Data.DataColumn col in table.Columns)  
        {  
           Console.WriteLine("{0} = {1}", col.ColumnName, row[col]);  
        }  
     Console.WriteLine("============================");  
     }  
  }  
}  

See Also

Retrieving Database Schema Information
ADO.NET Managed Providers and DataSet Developer Center