怎样实现模糊查询？请赐教！！！100分__String_getParameter_tmpbyte_department_request_

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怎样实现模糊查询？请赐教！！！100分

来源: 互联网发布时间：2015-05-31

本文导语: 我怎样才能实现模糊查询？比如说我现在有四个变量： String id=request.getParameter("txtStu_id").trim(); String name=request.getParameter("txtName").trim(); String grade=request.getParameter("dwnGrade").trim(); String department=request...

我怎样才能实现模糊查询？
比如说我现在有四个变量：
   String id=request.getParameter("txtStu_id").trim();
   String name=request.getParameter("txtName").trim();
   String grade=request.getParameter("dwnGrade").trim();
   String department=request.getParameter("dwnDepartment").trim();
   byte[] tmpbyte=id.getBytes("ISO8859_1");
   id=new String(tmpbyte);
   tmpbyte=name.getBytes("ISO8859_1");
   name=new String(tmpbyte);
   tmpbyte=grade.getBytes("ISO8859_1");
   grade=new String(tmpbyte);
   tmpbyte=department.getBytes("ISO8859_1");
   department=new String(tmpbyte);
要实现在数据库中的模糊查询，要求是 1，四个变量为空时，查出所有记录，2，随便一个变量有值，查出含有此内容的所有记录。
  高手有礼了！

没理由呀，
四个与一个是一样的呀
String sql="select * from table"
if (id==null){
sql=sql+ "where id like '%"+id+"%'";}

String id=request.getParameter("txtStu_id");
   String name=request.getParameter("txtName");
   String grade=request.getParameter("dwnGrade");
   String department=request.getParameter("dwnDepartment");
   byte[] tmpbyte;
   if(id!=null)
   {
       tmpbyte=id.trim().getBytes("ISO8859_1");
       id=new String(tmpbyte);
    }

   if(name!=null)
   {
       tmpbyte=name.trim().getBytes("ISO8859_1");
       name=new String(tmpbyte);
    }

   if(grade!=null)
   {
       tmpbyte=grade.trim().getBytes("ISO8859_1");
       grade=new String(tmpbyte);
    }

   if(department!=null)
   {
       tmpbyte=department.trim().getBytes("ISO8859_1");
       department=new String(tmpbyte);
    }

   String sStr = "select * from tablename " ;
   String sCondition = "" ;
   if (id!=null&&!id.equals(""))
sCondition +=" and ( id like '%" + id + "%')";
   if (name!=null&&!name.equals(""))
sCondition += " and ( name like '%" + name + "%')";
   if (grade!=null&&!grade.equals(""))
sCondition += " and ( grade like  '%" + grade + "%')";
   if (department!=null&&!department.equals(""))
sCondition += " and ( department = '%" + department + "')";
   if (!sCondition.equals(""))
sStr +="where "+ sCondition.substring(5);

这样你先试一试，如果还不行的话，请你告诉我具体是什么情况。

String id=request.getParameter("txtStu_id")==null?"":(request.getParameter("txtStu_id").equals("null")?"":request.getParameter("txtStu_id").trim());
   String name=request.getParameter("txtName")==null?"":(request.getParameter("txtName").equals("null")?"":request.getParameter("txtName").trim());
   String grade=request.getParameter("dwnGrade")==null?"":(request.getParameter("dwnGrade").equals("null")?"":request.getParameter("dwnGrade").trim());
   String department=request.getParameter("dwnDepartment")==null?"":(request.getParameter("dwnDepartment").equals("null")?"":request.getParameter("dwnDepartment").trim());
   byte[] tmpbyte=id.getBytes("ISO8859_1");
   id=new String(tmpbyte);
   tmpbyte=name.getBytes("ISO8859_1");
   name=new String(tmpbyte);
   tmpbyte=grade.getBytes("ISO8859_1");
   grade=new String(tmpbyte);
   tmpbyte=department.getBytes("ISO8859_1");
   department=new String(tmpbyte);

   String sStr = "select * from tablename " ;
   String sCondition = "" ;
   if (!id.equals(""))
sCondition +=" and (id like '%" + id + "%')";
   if (!name.equals(""))
sCondition += " and ( name like '%" + name + "%')";
   if (!grade.equals(""))
sCondition += " and ( grade like  '%" + grade + "%')";
   if (!department.equals(""))
sCondition += " and ( department = '%" + department + "')";
   if (!sCondition.equals(""))
sStr +="where "+ sCondition.substring(5);

试试

构造SQL语句时根据这四个参数是否为空来构造不行吗?
如：
String sql="select * from tablename ";
String temp="";
if(id!=nul && !id.equals("")) {
temp+=" id="+id;
}
if(name!=null && !name.equals("")) {
if(temp.length