How to change dynamically a blazor component

Question

I need to change the items from a list, the list is a component that shows numbers, but its numbers depend from other component named component2, and if component2 change her value component1 should reset and change to the new numbers. component2 is an other list.

this is component1 :

<div>
    <div class="d-flex listbox-box" @onclick="DropDown" style="height:@(height)px !important; width:@(width)px !important;padding:0px;">

        @if (ItemIsSelected)
        {
            <IterationItem height="@height" width="@width" _Iteration="Iteration[SelectedIndex]" />
        }else{
        <div class="align-self-center" style="width:100%;">
            <div class="float-end">
                <div class=" icon-container" style="transform: rotate(@(rotation)deg) !important;">
                    <i class="bi bi-chevron-compact-down icon-listbox"/>
                </div>
            </div>
        </div>
        }


      </div>
    @if (ShowDropDown && Iteration != null)
    {
            <div class="example dropdown-listbox" style="width:@(width)px !important;height:@(height * 3)px !important">
            @for (int i = 0; i < Iteration.Length-1; i++)
            {
                var index = i;
                        <div id="@i" value="@SelectedIndex" @onclick='eventargs => HandleValueChange(eventargs,index)'>
                            <IterationItem height="@height" width="@width" _Iteration="Iteration[i]" />
                        </div>
                        <hr class="listbox-item-separator"/>
            }
            </div>
    }
</div>

@code {
    int rotation = 0;
    [Parameter] public int SelectedIndex { get; set; } = -1;
    [Parameter] public bool ShowDropDown { get; set; } = false;
    [Parameter] public bool ItemIsSelected { get; set; } = false;
    [Parameter] public Iteration[] Iteration { get; set; }
    public int height { get; set; } = 40;
    public int width { get; set; } = 120;


    private void DropDown()
    {
        ShowDropDown = ShowDropDown ? false : true;

        if (ShowDropDown)
        {
            rotation = 180;
        }
        else
        {
            rotation = 0;
        }
    }

    protected void HandleValueChange(MouseEventArgs evt, int index)
    {
        SelectedIndex = index;
        DropDown();
        ItemIsSelected = true;

    }


}

and this is the event that make swap the numbers:

    void ClickHandler(int num)
    {
        _modelValue = num;
        _selectedModel =   
     XqueryFunctions.CreatrModelById(_modelValue,"");
    }

and this is how im trying to change it right now :

<ListBoxIteration Iteration="@_selectedModel.Iterations" />

@code {
    private string ProyectName { get; set; } = "Fred";
    int _modelValue;
    Model _selectedModel = new ();
    void ClickHandler(int num)
    {
        _modelValue = num;
        _selectedModel =   
        XqueryFunctions.CreatrModelById(_modelValue,"");
    }
}

Answer 1

The exact error you are seeing is due to the product expression not appearing directly inside an aggregated function. You should have taken the sum of this product directly. You might be fine just using the following LIMIT query:

SELECT customerid
FROM questions
GROUP BY customerid
ORDER BY SUM(product_quantity * price_per_item) DESC
LIMIT 1;

If there could be multiple customers tied for top sales, then use:

SELECT customerid
FROM questions
GROUP BY customerid
HAVING SUM(product_quantity * price_per_item) = (
    SELECT SUM(product_quantity * price_per_item)
    FROM questions
    GROUP BY customerid
    ORDER BY SUM(product_quantity * price_per_item) DESC
    LIMIT 1
);