这段代码是什么意思？

public class GuaHaoDao {

public ResultSet guahaoList(Connection con,PageBean pageBean,Patient patient,GuaHao guahao, String s_bGhDate, String s_eGhDate)throws Exception{
    StringBuffer sb=new StringBuffer("SELECT * FROM t_ghinfo g ,t_patient p ,t_user u WHERE p.userId=u.userId AND g.patientId=p.patientId");
    if(patient.getUserId()!=-1){            
        sb.append(" and p.userId = '"+patient.getUserId()+"'");
    }
    if(StringUtil.isNotEmpty(guahao.getPatientName())){
        sb.append(" and p.patientName like '%"+guahao.getPatientName()+"%'");
    }
    if(StringUtil.isNotEmpty(patient.getSex())){
        sb.append(" and p.sex ='"+patient.getSex()+"'");
    }
    if(StringUtil.isNotEmpty(s_bGhDate)){
        sb.append(" and TO_DAYS(g.date)>=TO_DAYS('"+s_bGhDate+"')");
    }
    if(StringUtil.isNotEmpty(s_eGhDate)){
        sb.append(" and TO_DAYS(g.date)<=TO_DAYS('"+s_eGhDate+"')");
    }
    if(StringUtil.isNotEmpty(guahao.getOfficeName())){
        sb.append(" and g.officeName ='"+guahao.getOfficeName()+"'");
    }
    //分页
    if(pageBean!=null){
        sb.append(" limit "+pageBean.getStart()+","+pageBean.getRows());
    }
    PreparedStatement pstmt=con.prepareStatement(sb.toString());
    return pstmt.executeQuery();
}
/**
 * 获取数据总条数
 * @param con
 * @param grade
 * @return
 * @throws Exception
 */
public int guahaoCount(Connection con,Patient patient, GuaHao guahao, String s_bGhDate, String s_eGhDate)throws Exception{
    StringBuffer sb=new StringBuffer("select count(*) as total from t_ghinfo g ,t_patient p ,t_user u WHERE p.userId=u.userId AND g.patientId=p.patientId");
    if(patient.getUserId()!=-1){            
        sb.append(" and p.userId = '"+patient.getUserId()+"'");
    }
    if(StringUtil.isNotEmpty(guahao.getPatientName())){
        sb.append(" and p.patientName like '%"+guahao.getPatientName()+"%'");
    }
    if(StringUtil.isNotEmpty(patient.getSex())){
        sb.append(" and p.sex ='"+patient.getSex()+"'");
    }
    if(StringUtil.isNotEmpty(s_bGhDate)){
        sb.append(" and TO_DAYS(g.date)>=TO_DAYS('"+s_bGhDate+"')");
    }
    if(StringUtil.isNotEmpty(s_eGhDate)){
        sb.append(" and TO_DAYS(g.date)<=TO_DAYS('"+s_eGhDate+"')");
    }
    if(StringUtil.isNotEmpty(guahao.getOfficeName())){
        sb.append(" and g.officeName ='"+guahao.getOfficeName()+"'");
    }
    PreparedStatement pstmt=con.prepareStatement(sb.toString());
    ResultSet rs=pstmt.executeQuery();
    if(rs.next()){
        return rs.getInt("total");
    }else{
        return 0;
    }
}

拼装两个sql执行，返回结果，难道是我理解错了

public ResultSet guahaoList(Connection con,PageBean pageBean,Patient patient,GuaHao guahao, String s_bGhDate, String s_eGhDate)throws Exception{//传入多个参数
StringBuffer sb=new StringBuffer("SELECT * FROM t_ghinfo g ,t_patient p ,t_user u WHERE p.userId=u.userId AND g.patientId=p .patientId");//建立字符串sql语句。用where进行条件查询
if(patient.getUserId()!=-1){

sb.append(" and p.userId = '"+patient.getUserId()+"'");
}
if(StringUtil.isNotEmpty(guahao.getPatientName())){
sb.append(" and p.patientName like '%"+guahao.getPatientName()+"%'");
}
if(StringUtil.isNotEmpty(patient.getSex())){
sb.append(" and p.sex ='"+patient.getSex()+"'");
}
if(StringUtil.isNotEmpty(s_bGhDate)){
sb.append(" and TO_DAYS(g.date)>=TO_DAYS('"+s_bGhDate+"')");
}
if(StringUtil.isNotEmpty(s_eGhDate)){
sb.append(" and TO_DAYS(g.date)<=TO_DAYS('"+s_eGhDate+"')");
}
if(StringUtil.isNotEmpty(guahao.getOfficeName())){
sb.append(" and g.officeName ='"+guahao.getOfficeName()+"'");
}
//分页
if(pageBean!=null){
sb.append(" limit "+pageBean.getStart()+","+pageBean.getRows());
}

    //以上的if语句全都是标示你的查询条件为不为空时你的String字符串进行拼接，形成完整的sql
PreparedStatement pstmt=con.prepareStatement(sb.toString());//用数据库你的db执行sql
return pstmt.executeQuery();//返回执行结果

}
/**

• 获取数据总条数
• @param con
• @param grade
• @return

• @throws Exception
  */

  //同上不再解释
  public int guahaoCount(Connection con,Patient patient, GuaHao guahao, String s_bGhDate, String s_eGhDate)throws Exception{
  StringBuffer sb=new StringBuffer("select count(*) as total from t_ghinfo g ,t_patient p ,t_user u WHERE p.userId=u.userId AND g.patientId=p.patientId");
  if(patient.getUserId()!=-1){
  
  sb.append(" and p.userId = '"+patient.getUserId()+"'");
  }
  if(StringUtil.isNotEmpty(guahao.getPatientName())){
  sb.append(" and p.patientName like '%"+guahao.getPatientName()+"%'");
  }
  if(StringUtil.isNotEmpty(patient.getSex())){
  sb.append(" and p.sex ='"+patient.getSex()+"'");
  }
  if(StringUtil.isNotEmpty(s_bGhDate)){
  sb.append(" and TO_DAYS(g.date)>=TO_DAYS('"+s_bGhDate+"')");
  }
  if(StringUtil.isNotEmpty(s_eGhDate)){
  sb.append(" and TO_DAYS(g.date)<=TO_DAYS('"+s_eGhDate+"')");
  }
  if(StringUtil.isNotEmpty(guahao.getOfficeName())){
  sb.append(" and g.officeName ='"+guahao.getOfficeName()+"'");
  }
  PreparedStatement pstmt=con.prepareStatement(sb.toString());
  ResultSet rs=pstmt.executeQuery();
  if(rs.next()){
  return rs.getInt("total");
  }else{
  return 0;
  }
  }

分页查询..................................

guahaoList查询sql的所以数据列表，guahaoCount查询sql语句符合条件的数量