Query and Combine Query by Number and Name in Java

1. First, define two text boxes on the front-end interface, and both text boxes have their own name values. The style of the text boxes is designed by themselves. When you click the query, you will jump to the action in the form form.

<DIV class="am-input-group am-input-group-sm" style="width:400px;">
       <form action="${pageContext.request.contextPath}/employee?action=select2" method="post">
		<div>
			<p>Name:</p>
			<SPAN  class="am-input-group-btn">
				<INPUT name="name" type="text" > //Define the type of the text box
				<input type="submit" value="query">//query button
			</SPAN>
		 </div>
		<div>
			<p>Employee ID:</p>
			<SPAN>
			        <INPUT  name="no"  type="text">
			</SPAN>
		</div>				  
	</form>
</DIV>

2. Write the action=select2 method in the servlet file in java. When you click the query, jump to this servlet file

else if(action != null && action.equals("select2")) {
		//Receive the value of the form
		String no = "";
		String name = "";
		/ / Determine whether the no and name text boxes are empty
		no=request.getParameter("no")==null?"":request.getParameter("no");
		name=request.getParameter("name")==null?"":request.getParameter("name");
		//Define employeeDao
		EmployeeDao employeeDao = new EmployeeDao();
		try {
			//Define a collection and call the query method from employeeDao
			List employeeList = employeeDao.chaxun(no, name);
			/*System.out.println(employeeList);*/
		        //Assign the value of employeeList to employeeList
			request.setAttribute("employeeList",employeeList);
		} catch (Exception e) {
			e.printStackTrace ();
		}
		//Jump to the manager.jsp file in employee after completion
		request.getRequestDispatcher("/employee/manager.jsp").forward(request, response);
	}

3. The method of writing the query in the Dao file, and the sql statement

public List chaxun(String no,String name) throws Exception{//Pass no and name as parameters
          //Write a sql statement not a String statement
    	  StringBuffer sql = new StringBuffer("select ID,TASK_USER_ID,TASK_DEPT_ID,EM_NO,EM_XM,EM_XB,EM_SR,EM_ZW,EM_ZZ,EM_SFZH from task_employee");
    	  Connection conn = null;
          PreparedStatement stmt = null;
          conn = getConn();
          //Define a collection of employeeList
          List employeeList = new ArrayList();
    	  try {	
    		        / / Judging no is not empty, when name is empty
			if(!no.equals("") && name.equals("")) {
				sql.append(" where EM_NO like '%"+no+"%'");
			}
			// Judging that name is not empty, when no is empty
			if(!name.equals("") && no.equals("")) {
				sql.append(" where EM_XM like '%"+name+"%'");	
			}
			//When it is judged that no and name are not empty
			if(!name.equals("") && !no.equals("")) {
				sql.append(" where EM_NO like'%"+no+"%'and EM_XM like '%"+name+"%'");
			}
			//Convert sql statement to String type
			String sql1 = sql.toString();
			conn = getConn();
			stmt = conn.prepareStatement(sql1);
			ResultSet rs = stmt.executeQuery();
			// Take the value from the result set and put it in the employee
			while (rs.next()) {
				Employee e = new Employee();
				e.setId (rs.getInt (1));
				e.setUserid (rs.getInt (2));
				e.setDeptide (rs.getInt (3));
				e.setNo(rs.getString(4));
				e.setName(rs.getString(5));
				e.setSex(rs.getString(6));
				e.setBirthday(rs.getDate(7));
				e.setDuty(rs.getString(8));
				e.setAddress(rs.getString(9));
				e.setNumber(rs.getString(10));
				employeeList.add(e);
			}
			
			
		} catch (SQLException e) {
			e.printStackTrace ();
		}
    	        //Return the collection of employeeList
		return employeeList;
    }