sql语句多条件简单写法

            string sql1 = @"SELECT     dbo.RenYuan.Name, dbo.BiYeLunWenKeTi.KeTiMing, dbo.BiYeLunWenKeTi.KeTiNeiRong, dbo.BiYeLunWenKeTi.KeTiId, dbo.BiYeLunWenKeTi.UserId, 
                      dbo.BiYeLunWenKeTi.BianJiShiJian, dbo.BiYeLunWenKeTi.Remark, dbo.BiYeLunWenKeTi.Stop, dbo.BiYeLunWenKeTi.XuanTiRenShu, 
                      RenYuan_1.Name AS BianJiRen, dbo.BiYeLunWenKeTi.YunXuRenShu, dbo.NianJi.NianJiName, dbo.KeTiNianJi.NianJiId, dbo.BiYeLunWenKeTi.TianJiaShiJian, 
                      dbo.JiaoShi.JiaoShiId
FROM         dbo.NianJi INNER JOIN
                      dbo.KeTiNianJi ON dbo.NianJi.NianJiId = dbo.KeTiNianJi.NianJiId RIGHT OUTER JOIN
                      dbo.JiaoShi INNER JOIN
                      dbo.RenYuan ON dbo.JiaoShi.RenYuanId = dbo.RenYuan.RenYuanId INNER JOIN
                      dbo.BiYeLunWenKeTi ON dbo.JiaoShi.JiaoShiId = dbo.BiYeLunWenKeTi.DaoShiId INNER JOIN
                      dbo.RenYuan AS RenYuan_1 ON dbo.BiYeLunWenKeTi.UserId = RenYuan_1.RenYuanId ON dbo.KeTiNianJi.KeTiId = dbo.BiYeLunWenKeTi.KeTiId   WHERE  1=1
";
                                                                                                                                                                   
            
            if (RenYuanId != "")
            {
                sql1 = sql1 + "and dbo.RenYuan.RenYuanId=‘" + RenYuanId + "‘ ";
            }
            if(txtTianJiaShiJian.Text!="")
            {
                    sql1 = sql1 + " and dbo.BiYeLunWenKeTi.TianJiaShiJian=‘" + txtTianJiaShiJian.Text + "‘";
            }