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DataBind Controls to Data in Delphi

DataBind to data in Delphi with standard data access components and controls.

The CData ODBC Driver for supports the ODBC standard to enable integration of live 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 data and query data from a simple visual component library (VCL) application, as well as from Delphi code.

Create a FireDAC Connection to 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.

The primary method for performing basic authentication is to provide your login credentials, as follows:

  • User: Set this to your username.
  • Password: Set this to your password.

Optionally, if you are making use of a sandbox environment, set the following:

  • UseSandbox: Set this to true if you are authenticating with a sandbox account.

Authenticating Using Account Number and License Key

Alternatively, you can authenticate using your account number and license key. Connect to data using the following:

  • AccountId: Set this to your Account Id. The Account Id is listed in the upper right hand corner of the admin console.
  • LicenseKey: Set this to your Avalara Avatax license key. You can generate a license key by logging into Avalara Avatax as an account adminstrator and navigating to Settings -> Reset License Key.

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

Create VCL Applications with Connectivity to Data

Follow the procedure below to start executing queries to 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 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, TotalTax FROM Transactions WHERE Code = '051349'
    • 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 with FireDAC Components

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

Connect to 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:

FDConnection1.ConnectionDefName := 'myavatax'; FDConnection1.Connected := true;

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.

FDQuery1.Open('select * from Transactions where Code = :Code',['051349']);

To execute a query that does not return a result set, such as a delete, use the ExecSQL method. The ExecSQL method will return an error if the query returns a result set. To retrieve the count of affected rows, use the TFD.RowsAffected property.

FDQuery1.ExecSQL('delete from Transactions where Id= :myId',['x12345']); i := FDQuery1.RowsAffected;