C# SQL多条件查询拼接技巧

   #region 多条件搜索时，使用List集合来拼接条件（拼接Sql）


            StringBuilder sql = new StringBuilder("select * from PhoneNum");
            List wheres = new List();
            if (cboGroup.SelectedIndex != 0)
            {
                wheres.Add(" ptypeid=" + cboGroup.Text.Split('|')[0]);
            }

            if (txtSearchName.Text.Trim().Length > 0)
            {
                 wheres.Add(" pname like '%" + txtSearchName.Text.Trim() + "%'");
            }

            if (txtSearchCellPhone.Text.Trim().Length > 0)
            {
                 wheres.Add(" pcellphone like '%" + txtSearchCellPhone.Text.Trim() + "%'");
            }


            //判断用户是否选择了条件
            if (wheres.Count > 0)
            {
                string wh = string.Join(" and ", wheres.ToArray());
                sql.Append(" where " + wh);
            }
            #endregion

 

 

 

            #region 多条件搜索使用带参数的sql语句

            StringBuilder sql = new StringBuilder("select * from PhoneNum");
            List wheres = new List();
            List listParameter = new List();

            if (cboGroup.SelectedIndex != 0)
            {
                wheres.Add(" ptypeid=@typeid ");
                listParameter.Add(new SqlParameter("@typeid", cboGroup.Text.Split('|')[0]));
            }

            if (txtSearchName.Text.Trim().Length > 0)
            {
                wheres.Add(" pname like @pname ");
                //pname like '%乔%'
                //pname liek '%'+@pname+'%'
                listParameter.Add(new SqlParameter("@pname", "%" + txtSearchName.Text.Trim() + "%"));
            }

            if (txtSearchCellPhone.Text.Trim().Length > 0)
            {
                wheres.Add(" pcellphone like @cellphone ");
                listParameter.Add(new SqlParameter("@cellphone", "%" + txtSearchCellPhone.Text.Trim() + "%"));
            }


            //判断用户是否选择了条件
            if (wheres.Count > 0)
            {
                string wh = string.Join(" and ", wheres.ToArray());
                sql.Append(" where " + wh);
            }

 

            SqlHelper.ExecuteDataTable(sql.ToString(), listParameter.ToArray());
            #endregion