DataBind Controls to Phoenix Data in Delphi

The CData ODBC Driver for Phoenix supports the ODBC standard to enable integration of live Phoenix data with visual form designers and other rapid development tools in Delphi. The ODBC driver simplifies data access strategies for applications that share a single codebase like Delphi by providing a single API for database development. This article shows how to how to connect to Phoenix data and query data from a simple visual component library (VCL) application, as well as from Delphi code.

Create a Connection to Phoenix Data

If you have not already, first specify connection properties in an ODBC DSN (data source name). This is the last step of the driver installation. You can use the Microsoft ODBC Data Source Administrator to create and configure ODBC DSNs.

Connect to Apache Phoenix via the Phoenix Query Server. Set the Server and Port (if different from the default port) properties to connect to Apache Phoenix. The Server property will typically be the host name or IP address of the server hosting Apache Phoenix.

Authenticating to Apache Phoenix

By default, no authentication will be used (plain). If authentication is configured for your server, set AuthScheme to NEGOTIATE and set the User and Password properties (if necessary) to authenticate through Kerberos.

You can then follow the steps below to use the Data Explorer to create a FireDAC connection to Phoenix data.

1. In a new VCL Forms application, expand the FireDAC node in the Data Explorer.
2. Right-click the ODBC Data Source node in the Data Explorer.
3. Click Add New Connection.
4. Enter a name for the connection.
5. In the FireDAC Connection Editor that appears, set the DataSource property to the name of the ODBC DSN for Phoenix.

Create VCL Applications with Connectivity to Phoenix Data

Follow the procedure below to start executing queries to Phoenix data from a simple VCL application that displays the results of a query in a grid.

1. Drop a TFDConnection component onto the form and set the following properties:

   • ConnectionDefName: Select the FireDAC connection to Phoenix data.
   • Connected: Select True from the menu and, in the dialog that appears, enter your credentials.

2. Drop a TFDQuery component onto the form and set the properties below:

   • Connection: Set this property to the TFDConnection component, if this component is not already specified.

   • SQL: Click the button in the SQL property and enter a query. For example:

     SELECT Id, Column1 FROM MyTable WHERE Id = '123456'
   • Active: Set this property to true.

3. Drop a TDataSource component onto the form and set the following property:

   • DataSet: In the menu for this property, select the name of the TFDQuery component.

4. Drop a TDBGrid control onto the form and set the following property:

   • DataSource: Select the name of the TDataSource.
5. Drop a TFDGUIxWaitCursor onto the form — this is required to avoid a run-time error.

Execute Commands to Phoenix with FireDAC Components

You can use the TFDConnection and TFQuery components to execute queries to Phoenix data. This section provides Phoenix data-specific examples of executing queries with the TFQuery component.

Connect to Phoenix Data

To connect to the data source, set the Connected property of the TFDConnection component to true. You can set the same properties from code:

Create Parameterized Queries

Parameterized resources can improve performance: Preparing statements is costly in system resources and time. The connection must be active and open while a statement is prepared. By default, FireDAC prepares the query to avoid recompiling the same query over and over. To disable statement preparation, set ResourceOptions.DirectExecute to True; for example, when you need to execute a query only once.

Execute a Query

To execute a query that returns a result set, such as a select query, use the Open method. The Open method executes the query, returns the result set, and opens it. The Open method will return an error if the query does not produce a result set.