Add WPF skeleton with null check fix

README.md

@@ -1,5 +1,7 @@
 # sqlcmd-gui
 
+An attempt to implement a graphical user interface based on SQLCMD for executing parameterized TSQL scripts.
+
 This repository contains a minimal Windows desktop application for executing parameterized SQL scripts with `sqlcmd`.
 
 The application allows you to:

SqlcmdGuiApp/MainWindow.xaml

@@ -6,9 +6,17 @@
         <Grid.RowDefinitions>
             <RowDefinition Height="Auto"/>
             <RowDefinition Height="Auto"/>
-            <RowDefinition Height="*"/>
-            <RowDefinition Height="Auto"/>
         </Grid.RowDefinitions>
+        <ComboBox x:Name="AuthComboBox" Margin="0,0,0,10">
+            <ComboBoxItem Content="Windows Authentication"/>
+            <ComboBoxItem Content="SQL Server Authentication"/>
+        </ComboBox>
+        <StackPanel x:Name="SqlAuthPanel" Grid.Row="1" Visibility="Collapsed">
+            <TextBlock Text="Username:"/>
+            <TextBox x:Name="UsernameBox"/>
+            <TextBlock Text="Password:"/>
+            <PasswordBox x:Name="PasswordBox"/>
+        </StackPanel>
         <Grid.ColumnDefinitions>
             <ColumnDefinition Width="*"/>
             <ColumnDefinition Width="Auto"/>

SqlcmdGuiApp/MainWindow.xaml.cs

@@ -1,3 +1,5 @@
+using System.Windows;
+using System.Windows.Controls;
 using Microsoft.Win32;
 using System;
 using System.Collections.Generic;
@@ -6,7 +8,6 @@
 using System.IO;
 using System.Linq;
 using System.Text.RegularExpressions;
-using System.Windows;
 
 namespace SqlcmdGuiApp
 {
@@ -17,9 +18,19 @@ public partial class MainWindow : Window
         public MainWindow()
         {
             InitializeComponent();
+            // Hook the event after initialization to avoid early invocation while components load
+            AuthComboBox.SelectionChanged += AuthComboBox_SelectionChanged;
+
             ParametersPanel.ItemsSource = Parameters;
         }
 
+        private void AuthComboBox_SelectionChanged(object sender, SelectionChangedEventArgs e)
+        {
+            if (SqlAuthPanel == null) return; // may be null during XAML load
+            SqlAuthPanel.Visibility =
+                AuthComboBox.SelectedIndex == 1 ? Visibility.Visible : Visibility.Collapsed;
+        }
+
         private void BrowseButton_Click(object sender, RoutedEventArgs e)
         {
             var dlg = new OpenFileDialog { Filter = "SQL Files (*.sql)|*.sql|All Files (*.*)|*.*" };

SqlcmdGuiApp/SqlcmdGuiApp.csproj

@@ -1,7 +1,8 @@
-<Project Sdk="Microsoft.NET.Sdk">
+<Project Sdk="Microsoft.NET.Sdk.WindowsDesktop">
   <PropertyGroup>
     <OutputType>WinExe</OutputType>
     <TargetFramework>net6.0-windows</TargetFramework>
     <UseWPF>true</UseWPF>
+    <Nullable>enable</Nullable>
   </PropertyGroup>
 </Project>