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Build a Simple VCL Application for BigQuery Data

How to build a simple VCL Application to view BigQuery data in RAD Studio using the CData FireDAC Components for BigQuery.

Embarcadero RAD Studio provides a development environment for Delphi and C++Builder applications. With the CData FireDAC Components for BigQuery, you gain access to live BigQuery data within RAD Studio, abstracting the data into tables, views, and stored procedures that can be used to both retrieve and update BigQuery data. This article will walk through connecting to BigQuery and creating a simple VCL application with the Form Designer.

Creating a VCL Application for BigQuery Data

The following instructions show how to use the Form Designer to create a simple VCL Forms application that shows the basic FireDAC objects needed to connect to BigQuery from any application.

The following example populates a TDBGrid control.

  1. Create a new VCL Forms Application.
  2. Drop a TFDPhysGoogleBigQueryDriverLink and TFDConnection object onto the form.
  3. Double-click the TFDConnection object. The FireDAC Connection Editor is displayed. Select "CData.GoogleBigQuery" in the DriverId menu and configure the connection properties.

    Google はOAuth 認証標準を使用します。個々のユーザーとしてGoogle API にアクセスするには、組み込みクレデンシャルを使うか、OAuth アプリを作成します。

    OAuth では、Google Apps ドメインのユーザーとしてサービスアカウントを使ってアクセスすることもできます。サービスカウントでの認証では、OAuth JWT を取得するためのアプリケーションを登録する必要があります。

    OAuth 値に加え、DatasetId、ProjectId を設定する必要があります。詳細はヘルプドキュメントの「はじめに」を参照してください。

  4. Drop a TFDQuery object onto the form and set the properties below:

    • Connection - Set this property to the TFDConnection object, if this object is not already specified.
    • SQL - Click the button in the SQL property and enter a query.
    • Active - Set this property to true.
  5. Drop a TDataSource object onto the form and set the following property:

    • DataSet - In the menu for this property, select the name of the TFDQuery object.
  6. Drop a TDBGrid control onto the form and set the following property:

    • DataSource - Select the name of the TDataSource.
  7. Drop a TFDGUIxWaitCursor onto the form. This is required to avoid a run-time error.

You now have an executable application that displays the results of the SQL Query set in the TFDQuery object.

 
 
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