DataBind Controls to MySQL データ in C++Builder

DataBind to MySQL のデータ in C++Builder with standard components and controls.

最終更新日:2023-06-12

The CData ODBC Driver for MySQL makes it easy to integrate connectivity to live MySQL 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 MySQL 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 MySQL 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.

Server およびPort プロパティがMySQL への接続には必須です。IntegratedSecurity をFALSE に設定した場合、User、Password も必須になります。 オプションで、Database を設定することもできます。Database は設定がない場合すべてのデータベースを使えるようになります。

パスワード方式によるSSH 接続

パスワード方式によるSSH接続時に必要なプロパティ一覧を以下に示します。

  • User: MySQL のユーザ
  • Password: MySQL のパスワード
  • Database: MySQL の接続先データベース
  • Server: MySQL のサーバー
  • Port: MySQL のポート
  • UserSSH: "true"
  • SSHAuthMode: "Password"
  • SSHPort: SSH のポート
  • SSHServer: SSH サーバー
  • SSHUser: SSH ユーザー
  • SSHPassword: SSH パスワード

接続文字列形式では以下のようになります。

User=admin;Password=adminpassword;Database=test;Server=mysql-server;Port=3306;UseSSH=true;SSHAuthMode=Password;SSHPort=22;SSHServer=ssh-server;SSHUser=root;SSHPassword=sshpasswd;

公開鍵認証方式方式によるSSH 接続

公開鍵認証によるSSH接続時に必要なプロパティ一覧を以下に示します。

  • User: MySQL のユーザ
  • Password: MySQL のパスワード
  • Database: MySQL の接続先データベース
  • Server: MySQL のサーバー
  • Port: MySQL のポート
  • UserSSH: "true"
  • SSHAuthMode: "Public_Key"
  • SSHClientCertType: キーストアの種類
  • SSHPort: SSH のポート
  • SSHServer: SSH サーバー
  • SSHUser: SSH ユーザー
  • SSHClientCert: 秘密鍵ファイルのパス

接続文字列形式では以下のようになります。

User=admin;Password=adminpassword;Database=test;Server=mysql-server;Port=3306;UseSSH=true;SSHAuthMode=Public_Key;SSHClientCertType=PUBLIC_KEY_FILE;SSHPort=22;SSHServer=ssh-server;SSHUser=root;SSHClientCert=C:\Keys\key.pem;

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

  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 MySQL.

Create VCL Applications with Connectivity to MySQL データ

Follow the procedure below to start querying MySQL のデータ 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 MySQL.
    • 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 ShipName, Freight FROM Orders
    • 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 MySQL with FireDAC Components

You can use the TFDConnection and TFQuery components to execute queries to MySQL のデータ. This section provides mysqlspecific examples of executing queries with the TFQuery component.

Connect to MySQL 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 MySQL ODBC Source"; FDConnection1->Connected = true;

To connect the TFDQuery component to MySQL 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 Orders where shipcountry = :ShipCountry"; FDQuery1->ParamByName("shipcountry")->AsString = "USA"; 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 Orders where shipcountry = :ShipCountry"; FDQuery1.ParamByName("shipcountry")->AsString = "USA"; 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 Orders 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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