2/Windows/AddMaterial.xaml

<Window x:Class="sql_pagining.Windows.AddMaterial"
        xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
        xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
        xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
        xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
        xmlns:local="clr-namespace:sql_pagining.Windows"
        mc:Ignorable="d"
        Title="AddMaterial" Height="450" Width="800">
    <Grid>
        <Grid.RowDefinitions>
            <RowDefinition Height="Auto" />
            <RowDefinition Height="Auto" />
            <RowDefinition Height="Auto" />
            <RowDefinition Height="Auto" />
            <RowDefinition Height="Auto" />
        </Grid.RowDefinitions>
        <Grid.ColumnDefinitions>
            <ColumnDefinition Width="Auto" />
            <ColumnDefinition Width="*" />
        </Grid.ColumnDefinitions>

        <TextBlock Grid.Row="0" Grid.Column="0" Text="Поиск материала:" Margin="10" />
        <TextBox x:Name="SearchTextBox" Grid.Row="0" Grid.Column="1" Margin="10" TextChanged="SearchTextBox_TextChanged" />

        <TextBlock Grid.Row="1" Grid.Column="0" Text="Материал:" Margin="10" />
        <ComboBox x:Name="MaterialComboBox" Grid.Row="1" Grid.Column="1" Margin="10" DisplayMemberPath="MaterialTitle"
              ItemsSource="{Binding allMaterials}" SelectedValuePath="ID" />

        <TextBlock Grid.Row="2" Grid.Column="0" Text="Количество:" Margin="10" />
        <TextBox x:Name="MaterialCountTextBox" Grid.Row="2" Grid.Column="1" Margin="10" />

        <Button x:Name="AddMaterialButton" Grid.Row="3" Grid.Column="0" Grid.ColumnSpan="2" Content="Добавить" Margin="10" Click="AddMaterialButton_Click" />
    </Grid>
</Window>