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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 uses the OAuth authentication standard. To access Google APIs on behalf of individual users, you can use the embedded credentials or you can register your own OAuth app.

    OAuth also enables you to use a service account to connect on behalf of users in a Google Apps domain. To authenticate with a service account, you will need to register an application to obtain the OAuth JWT values.

    In addition to the OAuth values, you will need to specify the DatasetId and ProjectId. See the "Getting Started" chapter of the help documentation for a guide to using OAuth.

  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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