本文转载：http://blog.csdn.net/limlimlim/article/details/8638080

   #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<string> wheres = new List<string>();
            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<string> wheres = new List<string>();
            List<SqlParameter> listParameter = new List<SqlParameter>();

            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

推荐C#中一套生成sql条件的类 

http://dotnet.chinaitlab.com/CSharp/746379_3.html

http://blog.csdn.net/dj1232090/article/details/2476224

http://blog.sina.com.cn/s/blog_3d7bed6501000c85.html

列表查询组件代码, 简化拼接条件SQL语句的麻烦

http://www.cnblogs.com/wuhuacong/archive/2007/11/19/964100.html

多条件搜索分页的实现

http://www.cnblogs.com/dedeyi/archive/2013/03/13/2957790.html