Linq中使用like和if

                    //根据输入内容绑定工作令号下拉框值，匹配与输入内容相似的值
                    var Tcn = (from ee in LinkToSQL.TasCom
                               from ff in LinkToSQL.PerPla
                               from gg in LinkToSQL.EmInfo
                               where SqlMethods.Like(ee.TasComNum, "%" + txtTasComNum.Text.Trim() + "%")
                               && ff.DesType == "常规"
                               && gg.EmName==(ff.DrawPerson==null?ff.DesPerson:ff.DrawPerson)
                               && ee.TasComID == ff.FK_TasComID
                               && gg.NaWhoSp == "zhangmingming"
                               && ee.IsDeleted == false
                               select ee.TasComNum).Distinct();
                    cbb_TasComNum.Items.Insert(0, "请选择");
                    cbb_TasComNum.SelectedIndex = 0;
                    cbb_TasComNum.Items.AddRange(Tcn.ToArray());