Delphi Database Tutorial: Connect, Query, and Update Your Database161

Delphi is a powerful programming language that can be used to create a wide variety of applications, including database applications. In this tutorial, we will learn how to connect to a database, query the database, and update the database using Delphi. We will use the FireDAC components to connect to the database, and we will use the SQL language to query and update the database.

Connect to a Database

The first step is to connect to the database. We can do this by creating a TFDConnection component and setting the following properties:* DriverID: The name of the database driver to use.
* Server: The name of the database server.
* Port: The port number of the database server.
* Database: The name of the database.
* User: The username to use to connect to the database.
* Password: The password to use to connect to the database.

Once we have set these properties, we can open the connection by calling the Open() method of the TFDConnection component.

Query the Database

Once we have connected to the database, we can query the database to retrieve data. We can do this by creating a TFDQuery component and setting the following properties:* Connection: The TFDConnection component that we used to connect to the database.
* SQL: The SQL statement that we want to execute.

Once we have set these properties, we can execute the query by calling the ExecSQL() method of the TFDQuery component. The ExecSQL() method will return a TFDDataSet component that contains the results of the query.

Update the Database

Once we have queried the database, we can update the database by modifying the data in the TFDDataSet component. We can then call the Update() method of the TFDDataSet component to save the changes to the database.

Example

The following code shows how to connect to a database, query the database, and update the database using Delphi:```delphi
// Create a TFDConnection component
FDConnection1 := (nil);
// Set the properties of the TFDConnection component
:= "MySQL";
:= "localhost";
:= 3306;
:= "test";
:= "root";
:= "";
// Open the connection
();
// Create a TFDQuery component
FDQuery1 := (nil);
// Set the properties of the TFDQuery component
:= FDConnection1;
("SELECT * FROM users");
// Execute the query
();
// Get the first record from the query
();
// Update the first record
("name").AsString := "John Doe";
// Save the changes to the database
();
// Close the connection
();
```

Conclusion

In this tutorial, we have learned how to connect to a database, query the database, and update the database using Delphi. We have also provided an example that shows how to use the FireDAC components and the SQL language to perform these operations.

2024-11-13

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