【C#プログラム入門】ポンコツ2人組がWPFでSQLiteデータベースを操作するプログラムに挑戦してみました！

<Window x:Class="WpfApp.MainWindow"
        xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
        xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
        Title="SQLite Sample" Height="350" Width="525">
    <Grid>
        <DataGrid x:Name="dataGrid" AutoGenerateColumns="True" HorizontalAlignment="Left" Height="200" Margin="10,10,0,0" VerticalAlignment="Top" Width="480"/>
        <Button Content="Insert" HorizontalAlignment="Left" Margin="10,220,0,0" VerticalAlignment="Top" Width="75" Click="Insert_Click"/>
        <Button Content="Update" HorizontalAlignment="Left" Margin="100,220,0,0" VerticalAlignment="Top" Width="75" Click="Update_Click"/>
        <Button Content="Delete" HorizontalAlignment="Left" Margin="190,220,0,0" VerticalAlignment="Top" Width="75" Click="Delete_Click"/>
        <Button Content="Select" HorizontalAlignment="Left" Margin="280,220,0,0" VerticalAlignment="Top" Width="75" Click="Select_Click"/>
    </Grid>
</Window>

using System;
using System.Data;
using System.Data.SQLite;
using System.Windows;

namespace WpfApp
{
    public partial class MainWindow : Window
    {
        private const string ConnectionString = "Data Source=sample.db";

        public MainWindow()
        {
            InitializeComponent();
            InitializeDatabase();
        }

        private void InitializeDatabase()
        {
            using (var connection = new SQLiteConnection(ConnectionString))
            {
                connection.Open();
                string createTableQuery = @"
                    CREATE TABLE IF NOT EXISTS SampleTable (
                        Id INTEGER PRIMARY KEY AUTOINCREMENT,
                        Name TEXT NOT NULL,
                        Age INTEGER NOT NULL
                    )";
                using (var command = new SQLiteCommand(createTableQuery, connection))
                {
                    command.ExecuteNonQuery();
                }
            }
        }

        private void Insert_Click(object sender, RoutedEventArgs e)
        {
            ExecuteNonQueryWithTransaction("INSERT INTO SampleTable (Name, Age) VALUES ('ポンコツ女子', 20)");
            SelectProc();
            MessageBox.Show("新規登録しました");
        }

        private void Update_Click(object sender, RoutedEventArgs e)
        {
            ExecuteNonQueryWithTransaction("UPDATE SampleTable SET Age = 21 WHERE Name = 'ポンコツ女子'");
            SelectProc();
            MessageBox.Show("更新しました");
        }

        private void Delete_Click(object sender, RoutedEventArgs e)
        {
            ExecuteNonQueryWithTransaction("DELETE FROM SampleTable WHERE Name = 'ポンコツ女子'");
            SelectProc();
            MessageBox.Show("削除しました");
        }

        private void Select_Click(object sender, RoutedEventArgs e)
        {
            SelectProc();
        }

        private void SelectProc()
        {
            DataTable dt = ExecuteQuery("SELECT * FROM SampleTable");
            dataGrid.ItemsSource = dt.DefaultView;
        }

        private void ExecuteNonQueryWithTransaction(string query)
        {
            using (var connection = new SQLiteConnection(ConnectionString))
            {
                connection.Open();
                using (var transaction = connection.BeginTransaction())
                {
                    try
                    {
                        using (var command = new SQLiteCommand(query, connection))
                        {
                            command.ExecuteNonQuery();
                        }
                        transaction.Commit();
                    }
                    catch (Exception ex)
                    {
                        transaction.Rollback();
                        MessageBox.Show($"Error: {ex.Message}");
                    }
                }
            }
        }

        private DataTable ExecuteQuery(string query)
        {
            using (var connection = new SQLiteConnection(ConnectionString))
            {
                connection.Open();
                using (var command = new SQLiteCommand(query, connection))
                {
                    using (var adapter = new SQLiteDataAdapter(command))
                    {
                        DataTable dt = new DataTable();
                        adapter.Fill(dt);
                        return dt;
                    }
                }
            }
        }
    }
}