ADO.NET Provider for GraphQL

Build 21.0.7940

Querying with the DataReader

The CData ADO.NET Provider for GraphQL implements two ADO.NET interfaces you can use to retrieve data from GraphQL: GraphQLDataAdapter and GraphQLDataReader objects. Whereas GraphQLDataAdapter objects retrieve a single result set of all the data that matches a query, GraphQLDataReader objects fetch data in subset increments as needed.

Using the GraphQLDataReader

The GraphQLDataReader retrieves data faster than the GraphQLDataAdapter because it can retrieve data in pages. As you read data from the GraphQLDataReader, it periodically requests the next page of results from the data source, if required. This causes results to be returned at a faster rate. The following example selects all the columns from the Users table:


string connectionString = "AuthScheme=OAuth;OAuthVersion=2.0;CallbackURL=http://localhost:33333;OauthClientId=MyOAuthClientId;OAuthClientSecret=MyOAuthClientSecret;OAuthAccessTokenURL=;";

using (GraphQLConnection connection = new GraphQLConnection(connectionString)) {
  GraphQLCommand cmd = new GraphQLCommand("SELECT * FROM Users", connection);
  GraphQLDataReader rdr = cmd.ExecuteReader();

  while (rdr.Read()) {
    Console.WriteLine(String.Format("\t{0} --> \t\t{1}", rdr["Name"], rdr["Email"]));


Dim connectionString As String = "AuthScheme=OAuth;OAuthVersion=2.0;CallbackURL=http://localhost:33333;OauthClientId=MyOAuthClientId;OAuthClientSecret=MyOAuthClientSecret;OAuthAccessTokenURL=;"

Using connection As New GraphQLConnection(connectionString)
  Dim cmd As New GraphQLCommand("SELECT * FROM Users", connection)

  Dim rdr As GraphQLDataReader = cmd.ExecuteReader()

  While rdr.Read()
    Console.WriteLine([String].Format(vbTab & "{0} --> " & vbTab & vbTab & "{1}", rdr("Name"), rdr("Email")))
  End While
End Using

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Build 21.0.7940