如何使用参数化来写SQL语句？传入的参数根据条件有多次拼接

using System;

using System.Collections.Generic;

using System.Linq;

using System.Web;

using System.Web.UI;

using System.Web.UI.WebControls;

using System.Data;

using CustomerControl;



public partial class productMake_productMakeList : System.Web.UI.Page

{

    const string vsKey = "searchCriteria"; //ViewState key

    protected void Page_Load(object sender, EventArgs e)

    {

        if (!IsPostBack)

        {

            string  s = "where isChecked=0";

            searchOrders(s);

        }

    }

    protected void Search_Click(object sender, EventArgs e)

    {

        AspNetPager1.CurrentPageIndex = 1;

        string s = " where ";

        string ischecked = dro_isPay.SelectedValue;

        if (ischecked == "false")

        {

            s += "isChecked=0";

        }

        else

        {

            s += "isChecked=1";

        }

        string type = dro_type.SelectedValue;

        switch (type)

        {

            case "1a1":

                s += " and whatWork='"+ type +"'";

            break;

            case "1a2":

                s += " and whatWork='" + type + "'";

            break;

            case "1a3":

                s += " and whatWork='" + type + "'";

            break;

            default:

            break;

        }

        string productname = tex_productName.Text.Trim();

        if (productname != "")

        {

            s += " and productName like '%" + productname + "%'";

        }

        string workername = tex_name.Text.Trim();

        if (workername != "")

        {

            s += " and workerName like '%" + workername + "%'"; //		sWhere	" where isChecked=0 and whatWork=1a1 and workerName like '%陈%'"	string



        }



        ViewState[vsKey] = s;

        searchOrders(s);

    }

    void searchOrders(string sWhere)

    {

        SqlDataSource1.SelectCommand = "select GGPRODUCT.ID,workID,productName,productPCS,price,total,reduce,productDate,GGPRODUCT.remark,checkedDate,workerName from GGPRODUCT left join worker on worker.ID=GGPRODUCT.workID " + sWhere + " order by GGPRODUCT.ID desc";

        DataView dv = (DataView)SqlDataSource1.Select(DataSourceSelectArguments.Empty);

        AspNetPager1.RecordCount = dv.Count;



        PagedDataSource pds = new PagedDataSource();

        pds.DataSource = dv;

        pds.AllowPaging = true;

        pds.CurrentPageIndex = AspNetPager1.CurrentPageIndex - 1;

        pds.PageSize = AspNetPager1.PageSize;

        Repeater1.DataSource = pds;

        Repeater1.DataBind();

    }



    protected void AspNetPager1_PageChanged(object src, EventArgs e)

    {

        searchOrders((string)ViewState[vsKey]);

    }





    }