เปลี่ยนชื่อหัวตารางในกริดวิว โดยการเขียนโค้ดอย่างไร

code VB

   Private Sub showdata()

        Dim sql As New SqlDataSource()
        Page.Controls.Add(sql)
        Dim sqla As String = "SELECT  Core_Competency.core as x1, Expect_Position.expect as x2, Score_core.score asx3 FROM   Evaluator INNER JOIN Score_core ON Score_core.id_evaluator = Evaluator.id_evaluator INNER JOIN Evaluatee ON Evaluatee.id_evaluatee = Evaluator.id_evaluatee INNER JOIN Core_Competency ON Core_Competency.id_core = Score_core.id_core INNER JOIN Expect_Position ON Expect_Position.id_core = Score_core.id_core INNER JOIN Head_Position ON Head_Position.id_head = Expect_Position.id_head WHERE Evaluatee.id_personnel = '" & txtidper.Text & "' AND Expect_Position.id_head ='" & txthead.Text & "'"
        With sql
            .ID = "sqlDataSource2"
            .ConnectionString = WebConfigurationManager.ConnectionStrings("EvaluationConnectionString").ConnectionString
            .SelectCommand = sqla
            .SelectCommandType = SqlDataSourceCommandType.Text

        End With
        GridView1.DataSource = sql
        GridView1.DataBind()
        With GridView1
            .Columns(0).HeaderText = "รหัสสมาชิก"
            .Columns(1).HeaderText = "ชื่อ สกุล"
            .Columns(2).HeaderText = "ที่อยู่"
        End With



    End Sub