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Build a Simple VCL Application for Presto Data

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

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

Creating a VCL Application for Presto 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 Presto from any application.

The following example populates a TDBGrid control.

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

    Set the Server and Port connection properties to connect, in addition to any authentication properties that may be required.

    To enable TLS/SSL, set UseSSL to true.

    Authenticating with LDAP

    In order to authenticate with LDAP, set the following connection properties:

    • AuthScheme: Set this to LDAP.
    • User: The username being authenticated with in LDAP.
    • Password: The password associated with the User you are authenticating against LDAP with.

    Authenticating with Kerberos

    In order to authenticate with KERBEROS, set the following connection properties:

    • AuthScheme: Set this to KERBEROS.
    • KerberosKDC: The Kerberos Key Distribution Center (KDC) service used to authenticate the user.
    • KerberosRealm: The Kerberos Realm used to authenticate the user with.
    • KerberosSPN: The Service Principal Name for the Kerberos Domain Controller.
    • KerberosKeytabFile: The Keytab file containing your pairs of Kerberos principals and encrypted keys.
    • User: The user who is authenticating to Kerberos.
    • Password: The password used to authenticate to Kerberos.

  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.