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DataBind Controls to Azure Table データ in C++Builder
DataBind to Azure Table のデータ in C++Builder with standard components and controls.
最終更新日：2023-06-12The CData ODBC Driver for Azure Table makes it easy to integrate connectivity to live Azure Table のデータ with standard data access components in C++Builder. This article shows how to create a simple visual component library (VCL) application in C++Builder that connects to Azure Table のデータ, executes queries, and displays the results in a grid. An additional section shows how to use FireDAC components to execute commands from code.
Create a Connection to Azure Table データ
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.
Account プロパティをストレージアカウント名に設定し、ストレージアカウントのAccessKey を設定して接続します。これらの値を取得する方法は次のとおりです。
ストレージをBackend として使用している場合（デフォルト）
- Azure ポータルにログインし、左側の「サービス」メニューで「ストレージアカウント」を選択します。
- ストレージアカウントがない場合は、「追加」ボタンをクリックしてアカウントを作成します。
- 使用するストレージアカウントのリンクをクリックし、「設定」の「アクセスキー」を選択します。 「アクセスキー」ウィンドウには、ストレージアカウント名とCData 製品で使用するキー（接続にはkey1またはkey2のどちらかを使用できます）が含まれています。これらのプロパティは、それぞれAccount とAccessKey 接続プロパティにマッピングされます。
Azure SQL への接続
- Azure ポータルにログインし、左側の「サービス」メニューで「Azure Cosmos DB」を選択します。
- 使用するCosmos DB アカウントのリンクをクリックし、「設定」の「接続文字列」を選択します。 「接続文字列」ウィンドウには、Cosmos DB アカウント名とCData 製品で使用する主キーが含まれています。これらのプロパティは、それぞれAccount とAccessKey 接続プロパティにマッピングされます。
You can then follow the steps below to use the Data Explorer to create a FireDAC connection to Azure Table.
- In a new VCL Forms application, expand the FireDAC node in the Data Explorer.
- Right-click the ODBC Data Source node in the Data Explorer.
- Click Add New Connection.
- Enter a name for the connection.
- In the FireDAC Connection Editor that appears, set the DataSource property to the name of the ODBC DSN for Azure Table.
Create VCL Applications with Connectivity to Azure Table データ
Follow the procedure below to start querying Azure Table のデータ from a simple VCL application that displays the results of a query in a grid.
-
Drop a TFDConnection component onto the form and set the following properties:
- ConnectionDefName: Select the FireDAC connection to Azure Table.
- Connected: Select True from the menu and, in the dialog that appears, enter your credentials.
-
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 Name, Price FROM NorthwindProducts- Active: Set this property to true.
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.
-
Drop a TDBGrid control onto the form and set the following property:
- DataSource: Select the name of the TDataSource.
- Drop a TFDGUIxWaitCursor onto the form — this is required to avoid a run-time error.
Execute Commands to Azure Table with FireDAC Components
You can use the TFDConnection and TFQuery components to execute queries to Azure Table のデータ. This section provides azurespecific examples of executing queries with the TFQuery component.
Connect to Azure Table データ
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 = "CData Azure Table ODBC Source";
FDConnection1->Connected = true;
To connect the TFDQuery component to Azure Table のデータ, set the Connection property of the component. When a TFDQuery component is added at design time, its Connection property is automatically set to point to a TFDConnection on the form, as in the application above.
Create Parameterized Queries
To create a parameterized query, use the following syntax below:
FDQuery1->SQL->Text = "select * from NorthwindProducts where shipcity = :ShipCity";
FDQuery1->ParamByName("shipcity")->AsString = "New York";
query->Open();
The example above binds a string-type input parameter by name and then opens the dataset that results.
Prepare the Statement
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->SQL->Text := "select * from NorthwindProducts where shipcity = :ShipCity";
FDQuery1.ParamByName("shipcity")->AsString = "New York";
FDQuery1->Open();
To execute a query that does not return a result set, 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.
FDQ.SQL.Text := "delete from NorthwindProducts where Id = :Id";
FDQuery1->Params->Items[0]->AsString = "x12345";
FDQuery1->ExecSQL();
AnsiString i = FDQuery1->RowsAffected;
Related Articles
Below you can find other articles for using the CData ODBC Driver with RAD Studio, Delphi, and C++ Builder.
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