如何使用LIKE和%%运算符查询和过滤Web表单中的数据？

Question

I want to filter and select data from sql server in my web form by using LIKE and % % operator

I searched in stackoverflow solutions but i cannot find the solution to my case and i tried alot but its not working correctly. This is my code:

protected void BtnSearch_Click(object sender, EventArgs e)
            {
                string sql = @" SELECT [appt_id],visitor_name,mobile ,work_place.work_place_name as work_place_name,days.day as day,date,[time],[subject],[duration],appointment_place.appt_place as appt_place 
                               FROM [Appointments] 
                               inner join days on days.day_id = Appointments.day_id 
                               inner join appointment_place on appointment_place.appt_place_id =Appointments.appt_place_id
                               inner join work_place on work_place.work_place_id = Appointments.work_place_id 
                               where 1=1 ";

                string condition = "";
                string orderby = "order by date";
                // orderby += "order by appointments.time";

                if (txtVisitorName.Text != "")
                {
                    condition += " and appointments.visitor_name like '" + txtVisitorName.Text + "'";
                }
                if (txtsubject.Text != "")
                {
                    condition += " and appointments.subject like '" + txtsubject.Text + "'";
                }
                if (txtMobileNo.Text != "")
                {
                    condition += " and appointments.mobile ='" + txtMobileNo.Text + "'";
                }


                DataTable dt = func.fireDatatable(string.Format(sql + condition + orderby));
                gvappt.DataSource = dt;
                gvappt.DataBind();
            }

I expect the output of code to use LIKE and %% to search visitors name or subject contains part of name or part of subject ?

Answer 1

I found the correct answer to my question :

if (txtDocSubject.Text != "")
    {
    condition +=" and Documents.Document_subject like '%"+txtDocSubject.Text+"%'";
    }