WITH temporaryTable (averageValue) as

    (SELECT avg(Attr1)

    FROM Table)

    SELECT Attr1

    FROM Table, temporaryTable

    WHERE Table.Attr1 > temporaryTable.averageValue;

SELECT CONCAT(first_name, ' ', last_name) AS full_name

FROM Customers;

<asp:CheckBox ID="Column1CheckBox" runat="server" AutoPostBack="true" OnCheckedChanged="ShowSelectedColumn" Text="Column 1" />

<asp:CheckBox ID="Column2CheckBox" runat="server" AutoPostBack="true" OnCheckedChanged="ShowSelectedColumn" Text="Column 2" />

<!-- Add more checkboxes for each column -->

​

<asp:GridView ID="DataGrid" runat="server" AutoGenerateColumns="False">

    <!-- Define BoundFields for each column -->

</asp:GridView>

Imports System.Data.SqlClient

Imports System.Data

​

Public Class ColumnSelection

    Inherits System.Web.UI.Page

​

    Dim connectionString As String = "YourConnectionStringHere"

​

    Protected Sub Page_Load(ByVal sender As Object, ByVal e As System.EventArgs) Handles Me.Load

        If Not IsPostBack Then

            ' Load initial data into the GridView with all columns visible.

            BindGridViewWithAllColumns()

        End If

    End Sub

​

    Protected Sub ShowSelectedColumn(ByVal sender As Object, ByVal e As EventArgs)

        ' Determine which checkbox was selected.

        Dim selectedCheckBox As CheckBox = DirectCast(sender, CheckBox)

​

        ' Update the GridView's visibility based on the selected checkbox.

        If selectedCheckBox.ID = "Column1CheckBox" AndAlso Column1CheckBox.Checked Then

            DataGrid.Columns(0).Visible = True ' Show Column 1

            DataGrid.Columns(1).Visible = False ' Hide Column 2

            ' Hide other columns as needed

        ElseIf selectedCheckBox.ID = "Column2CheckBox" AndAlso Column2CheckBox.Checked Then

            DataGrid.Columns(0).Visible = False ' Hide Column 1

            DataGrid.Columns(1).Visible = True ' Show Column 2

            ' Hide other columns as needed

        Else

            ' If no checkbox is selected or multiple checkboxes are selected,

            ' show all columns by default.

            BindGridViewWithAllColumns()

        End If

    End Sub

​

    Private Sub BindGridViewWithAllColumns()

        Using connection As New SqlConnection(connectionString)

            Dim sql As String = "SELECT * FROM YourTableNameHere"

            Dim adapter As New SqlDataAdapter(sql, connection)

            Dim dt As New DataTable()

​

            Try

                connection.Open()

                adapter.Fill(dt)

                DataGrid.DataSource = dt

                DataGrid.DataBind()

            Catch ex As Exception

                ' Handle the exception (e.g., display an error message)

            End Try

        End Using

    End Sub

End Class