vcl-405738-expresscrossplatformlibrary-vcl-backend-database-engines-vcl-backend-postgresql-support.md
PostgreSQL is an open-source relational database management system. You can connect TdxDashboard/TdxDashboardControl and TdxReport components to PostgreSQL databases using the TdxBackendDatabaseSQLConnection component.
In this topic…
Tip
Prerequisites : To use this guide, your development environment should include a configured PostgreSQL server component and test database table.
Prerequisites — Install PostgreSQL Components & Create a Test Database
Download a supported PostgreSQL server package for Microsoft Windows (18.1, for example): Download PostgreSQL.
Install PostgreSQL components:
Run the installed pgAdmin app and expand the Servers node in the Object Explorer.
Select the Databases node and create a new database (press Alt + Shift + N or right-click the node and select Create → Database… ):
Specify a database name (dashboard_test) and click Save.
Run the Query Tool (press Alt + Shift + Q or right-click dashboard_test and select Query Tool ):
Execute the following SQL query to create an empty products test table:
Execute the following SQL query to populate the table:
Execute all SQL queries listed in this section to create a new PostgreSQL user and all necessary permissions. Run each line as a separate query according to the comments:
Create a new project and place TdxDashboardControl and TdxBackendDataConnectionManager components on a form.
Double-click the TdxBackendDataConnectionManager component on the form to open the Collection Editor dialog, click the Add button, and select the Database (SQL) option to create a TdxBackendDatabaseSQLConnection component:
The previously added TdxBackendDatabaseSQLConnection component connects to the source PostgreSQL database using a connection string. To configure this component and specify a valid connection string, add a TcxButton component to a form and handle the component’s OnClick event as demonstrated in the following code example:
uses
dxDashboard.Control, // Declares the TdxDashboardControl component
dxBackend.ConnectionString.SQL; // Declares the TdxBackendDatabaseSQLConnection component
// ...
procedure TMyForm.cxDisplayDesignerButtonClick(Sender: TObject);
begin
dxBackendDatabaseSQLConnection1.Active := False; // Terminates the current connection (if one exists)
// Specify a user-friendly data connection name (for end-user dialogs) and a valid connection string:
dxBackendDatabaseSQLConnection1.DisplayName := 'PostgreSQL Database Connection';
dxBackendDatabaseSQLConnection1.ConnectionString :=
'XpoProvider=Postgres;' + // Specifies the database engine type
'Server=127.0.0.1;' + // Specifies the database host IP address
'User ID=myuser;' + // Specifies a valid user name
'Password=123;' + // Specifies the corresponding password for the user name
'Database=dashboard_test;' + // Specifies the target database name
'Encoding=UNICODE'; // Sets UTF-8 as the required encoding
dxBackendDatabaseSQLConnection1.Active := True; // Connects to the test database
dxDashboardControl1.ShowDesigner; // Displays the "Dashboard Designer" dialog
end;
#include "dxDashboard.Control.hpp" // Declares the TdxDashboardControl component
#include "dxBackend.ConnectionString.SQL.hpp" // Declares the TdxBackendDatabaseSQLConnection component
// Add the following linker directives to the corresponding CPP source file:
#pragma link "dxDashboard.Control" // Required to use dxDashboard.Control.hpp declarations
#if defined(_WIN64) // Required to use dxBackend.ConnectionString.SQL.hpp declarations
#pragma link "dxBackend.ConnectionString.SQL.o"
#else
#pragma link "dxBackend.ConnectionString.SQL.obj"
#endif
// ...
void __fastcall TMyForm::cxDisplayDesignerButtonClick(TObject *Sender)
{
dxBackendDatabaseSQLConnection1->Active = false; // Terminates the current connection (if one exists)
// Specify a user-friendly data connection name (for end-user dialogs) and a valid connection string:
dxBackendDatabaseSQLConnection1->DisplayName = "PostgreSQL Database Connection";
dxBackendDatabaseSQLConnection1->ConnectionString =
L"XpoProvider=Postgres;" // Specifies the database engine type
L"Server=127.0.0.1;" // Specifies the database host IP address
L"User ID=myuser;" // Specifies a valid user name
L"Password=123;" // Specifies the corresponding password for the user name
L"Database=dashboard_test;" // Specifies the target database name
L"Encoding=UNICODE"; // Sets UTF-8 as the required encoding
dxBackendDatabaseSQLConnection1->Active = true; // Connects to the test database
dxDashboardControl1->ShowDesigner(); // Displays the "Dashboard Designer" dialog
}
Tip
Alternatively, you can select the created TdxBackendDatabaseSQLConnection component in the Collection Editor and specify all required settings using the Object Inspector.
The application form contains TdxDashboardControl and TcxButton components:
Run the built executable file and click the previously added button to display the DevExpress Dashboard Designer dialog. Click the hamburger button, select the Data Sources item, and click the Add link in the DATA SOURCES pane:
Click the Create data source… link in the Add Data Source modal dialog:
Select Database in the Dashboard Data Source Wizard modal dialog and click Next :
The wizard displays the created data connection component using its display name specified earlier.
Click Next and use the Run Query Builder… option:
Expand the AVAILABLE TABLES AND VIEWS node to browse tables from the connected database:
If the AVAILABLE TABLES AND VIEWS node contains the products test table created within the dashboard_test database, the created PostgreSQL connection is successful.
Review the following tutorials to get started with TdxDashboardControl and TdxReport components:
Create a Dashboard Using the Designer DialogCreate a dashboard application: configure Bubble Map and Chart dashboard items, and bind them to data at design time.Create a Table Report Using the Report WizardCreate a simple report application: define a table report layout and bind it to data using the Report Wizard dialog at design time.
Refer to the following topics for step-by-step instructions on using corresponding database systems for ExpressReports and ExpressDashboards:
VCL Dataset and Data Source ComponentsThe TdxBackendDataSetJSONConnection component allows you to bind TdxDashboard/TdxDashboardControl and TdxReport to one or multiple datasets (TdxMemData, TFDTable, TFDQuery, and other TDataSet descendants) using TDataSource components.In-Memory/Remote Web ServiceThe TdxBackendInMemoryJSONConnection component allows you to bind TdxDashboard/TdxDashboardControl and TdxReport components to JSON data defined in code or loaded from a remote Web API service endpoint.SQLiteSQLite is a file-based relational database engine.Microsoft SQL/Azure DatabasesMicrosoft SQL Server and Azure SQL Database are proprietary relational database management systems developed by Microsoft.
Oracle DatabaseOracle Database is a proprietary multi-model database management system developed by the Oracle Corporation.MySQLMySQL is an open-source relational database management system developed by the Oracle Corporation.FirebirdFirebird is an open-source SQL relational database management system.
Footnotes
See Also