前台页面查询参数多的话,建议将其封装成querybean传到DAO层,在DAO层构建SQL语句:例子

最新推荐文章于 2022-07-18 19:37:42 发布

原创最新推荐文章于 2022-07-18 19:37:42 发布 · 4k 阅读

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CC 4.0 BY-SA版权

文章标签：

#dao #sql #string #null

该博客展示了如何将前端查询参数封装到UserFormBean中，并在DAO层根据这些参数动态构建SQL查询语句，以实现更加灵活的查询功能。在示例中，当用户名或兴趣不为空时，它们会被加入到SQL的WHERE子句中，最后按USERID进行排序。

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public List<UserFormBean> getAllUserInfo(UserFormBean userFormBean)
{
  StringBuffer sql = new StringBuffer("select USERID,USERNAME,PASSWORD,REALNAME,SEX,INTEREST,DEGREE,INTRO,STATUS from demo_userinfo where 1=1");
  String username = userFormBean.getUserName();
  String interest = userFormBean.getInterest();

  //如果查询条件不空，则增加此条件；
  if(username != null && !"".equals(username)){
   sql.append(" and username like '%"+username+"%'");
  }
  if(interest != null && !"".equals(interest)){
   sql.append(" and interest = '"+interest+"'");
  }
  sql.append(" order by USERID");
  PreparedStatement pstm = null;
  ResultSet rs = null;
  Connection con = null;
  List<UserFormBean> resultList = new ArrayList<UserFormBean>();
  try
  {
   con = DBConnection.getConnection();
//   System.out.println("---------------sql="+sql);
   pstm = con.prepareStatement(sql.toString());
   rs = pstm.executeQuery();

   while (rs.next())
   {
    UserFormBean userInfo = new UserFormBean();
    userInfo.setUserId(rs.getLong("USERID"));
    userInfo.setUserName(rs.getString("USERNAME"));
    userInfo.setPassWord(rs.getString("PASSWORD"));
    userInfo.setName(rs.getString("REALNAME"));
    userInfo.setSex(rs.getString("SEX"));
    userInfo.setInterest(rs.getString("INTEREST"));
    userInfo.setDegree(rs.getString("DEGREE"));
    userInfo.setIntro(rs.getString("INTRO"));
    userInfo.setStatus(rs.getString("STATUS"));
    resultList.add(userInfo);
   }
//System.out.println("---------------------ok");
  } catch (SQLException e)
  {
   e.printStackTrace();
  } finally
  {
   try{
     rs.close();
     pstm.close();
     con.close();
   }catch(SQLException e){
    e.printStackTrace();
   }
  }

return resultList;
}