选择每个类别的最新3条新闻（MySQL-PHP）

Question

我想从每个类别中选择最后3条新闻，

我尝试在此SQL代码中进行限制，但它只给了我所有类别中的最后3条新闻

 private HorizontalAlignment _CategoryHorizontalAlignment;
    public HorizontalAlignment CategoryHorizontalAlignment
    {
        get { return _CategoryHorizontalAlignment; }
        set
        {
            _CategoryHorizontalAlignment = value;
            NotifyPropertyChanged("CategoryHorizontalAlignment");
        }
    }

CategoryHorizontalAlignment = HorizontalAlignment.Right;



<DataTemplate x:Key="GantButtonObservableClassTemplate" >
        <StackPanel Orientation="Vertical" HorizontalAlignment="Left" VerticalAlignment="Bottom">

            <Label Content="{Binding Category}" Height="20"
                       Width="{Binding Duration}" 
                       Margin="{Binding Margin, UpdateSourceTrigger=PropertyChanged}"
                       Background="{Binding CustomBackgroundColor}" 
                       FontSize="{Binding GantChartFontSize, UpdateSourceTrigger=PropertyChanged}" Foreground="Black" FontWeight="DemiBold"
                       VerticalAlignment="Center" VerticalContentAlignment="Center" >
                <Label.Style>
                    <Style TargetType="Label">
                        <Setter Property="Template">
                            <Setter.Value>
                                <ControlTemplate TargetType="Label">
                                    <Border x:Name="_brdMain" 
                                            BorderThickness="{TemplateBinding BorderThickness}"
                                            BorderBrush="{TemplateBinding BorderBrush}" 
                                            Background="{TemplateBinding Background}"
                                            CornerRadius="7,7,7,7" Padding="{Binding CategoryPadding, UpdateSourceTrigger=PropertyChanged}">
                                        <ContentPresenter  HorizontalAlignment="{Binding CategoryHorizontalAlignment, UpdateSourceTrigger=PropertyChanged}" VerticalAlignment="Center" />
                                    </Border>
                                </ControlTemplate>
                            </Setter.Value>
                        </Setter>
                    </Style>
                </Label.Style>
            </Label>
        </StackPanel>
    </DataTemplate>

任何解决方案吗？