WHERE子句中的MySQL陈述式错误

Question

I am trying to get a value "startDate" and "endDate" from my form:

<form>
        <input id="startDate"/>                     
        <input id="endDate"/>
    </form

The form is connected to a javascript, which from there goes to a MySQL database. The problem is that every time I run SQL query in my servlet i get the following error:

SQLException caught: Unknown column 'startDate' in 'where clause'

Can anybody see what I am doing wrong? have a nice day from Julie

EDITED CODE: I have tried to edited my code. I now get the error at: Date startDate; , where it says: "Duplicate local variable startDate". That is of course because I have String startDate = req.getParameter("startDate"); . I dont have to use this anymore? package WorkPackage;

import java.io.*;
import java.sql.*;
import javax.servlet.*;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.*;

@WebServlet("/getHoursSQL")
public class getHoursSQL extends HttpServlet{

    private static final long serialVersionUID = 1L;

    @Override
    protected void doGet(HttpServletRequest request, HttpServletResponse response)
            throws ServletException, IOException {
        doPost(request, response);
    }

    public void doPost(HttpServletRequest req, HttpServletResponse res) 
        throws ServletException, IOException{

        String connectionURL = "jdbc:mysql://localhost/NekiWork";
        Connection connection=null;
        String startDate = req.getParameter("startDate");
        String endDate= req.getParameter("endDate");
        try {
            //Load database driver
            Class.forName("com.mysql.jdbc.Driver");
            //Connection to the database
            connection = DriverManager.getConnection(connectionURL, "root", ""); 
            //Getting the data from database
            Date startDate;                                             
            String sql = "SELECT *, (Day_hours + (Day_minutes / 60)) AS Allday_hours FROM Workdata WHERE Date = ?";
            PreparedStatement pst = connection.prepareStatement(sql);
                pst.setDate(1,startDate);
                //pst.setString(2,endDate);
            //Show the result from database
                ResultSet rs = pst.executeQuery();

            float Allday_hours_sum = 0;
                while (rs.next()){                                      
                    Allday_hours_sum += rs.getFloat("Allday_hours"); 


            }   
                res.setContentType("text/html;charset=UTF-8");          
                res.getWriter().print(Allday_hours_sum); 


            pst.close();


        }
        catch(ClassNotFoundException e){

            System.out.println("Couldn't load database driver: " + e.getMessage());
        }
        catch(SQLException e){
            System.out.println("SQLException caught: " + e.getMessage());
        }
        catch (Exception e){
            System.out.println(e);
        }
        finally {

            try {
                if (connection != null) connection.close();
            }
            catch (SQLException ignored){
                System.out.println(ignored);
            }
        }
    }
}

EDITED: This is how my database looks like: http://postimg.org/image/3sbzplg9d/

This is my javascript where I am getting some values out from my calendar:

<form>
        <input id="startDate"/>                     
        <input id="endDate"/>
    </form>
    <div id="startresult"></div>
    <div id="endresult"></div>
    <script>

    $(function(){
        $("#startDate").datepicker({
            dateFormat: 'yy-mm-dd',
            onSelect: function(dateText,inst){
                $('.selected-date').html(dateText);

                $.ajax({
                      url: "../getHoursSQL",
                      type: "post",
                      data: JSON,
                      success: function(data){
                          start: $("#startDate").val();
                          alert("success");
                          $("#startresult").html(data);

                      },
                      error:function(){
                          alert("failure");
                          $("#startresult").html('there is error while submit');
                      }  
                    });
            }
        });
    });

    $(function(){
            $("#endDate").datepicker({
                dateFormat: 'yy-mm-dd',
                onSelect: function(dateText,inst){
                    $('.selected-date').html(dateText);

                    $.ajax({
                          url: "../getHoursSQL",
                          type: "post",
                          data: JSON,
                          success: function(data){
                              end: $("#endDate").val();
                              alert("success");
                              $("#endresult").html(data);
                          },
                          error:function(){
                              alert("failure");
                              $("#result").html('there is error while submit');
                          }  
                        });
                }
            });
        });

</script>

Answer 1

As mentioned in the error it couldn't find the column in the table. Please check your table Workdata has field startDate

And also it is not good to pass date as String and also be careful to use = operator to compare date or datetime filed. My advise is to compare datetime use BETWEEN operator.

... WHERE startDate BETWEEN value1 AND value2

Answer 2

if you want to get data then you should this instead.

Date startDate;
//use SqlDate instead of string.

String sql = "SELECT *, (Day_hours + (Day_minutes / 60)) AS Allday_hours FROM Workdata WHERE Date = ?";
PreparedStatement pst = connection.prepareStatement(sql);
pst.setDate(1,startDate);

Now you have something in your output as you have date column in your table.

UPDATE :

If you want to use String datatype for date parameter.. Remove Date startDate and keep it what you have.. After that Parse your date using SimpleDateFormatter.

For EG.

String startDate = req.getParameter("Date");
SimpleDateFormat sdf = new SimpleDateFormat("yyyy-MM-dd");
//surround below line with try catch block as below code throws checked exception
Date start = sdf.parse(startDate);
out.println(sdf.format(startDate)); //this is what you want yyyy-MM-dd  

Thanks..

Answer 3

As far as I can tell from your image (it's rather cluttered, far too much information) there's no column called startDate in table Workdata. All columns in an SQL statement must actually exist in the appropriate tables.

Did you mean column Date? If you did, you shouldn't use

pst.setString(1, startDate);

because that's only good for setting string columns (varchar, longtext, etc). Instead, you should use

pst.setDate(1, startDate);

where startDate here is a java.sql.Date , not a String

EDIT:

In response to your updates, I have updated my answer.

The line

Date startDate;

surely won't compile, as startDate is already a declared as a String. Even if you changed the name, you have not set the date given in the request parameter.

You'll need to do something like this:

SimpleDateFormat format = new SimpleDateFormat("yyyy-MM-dd");
Date startDate = format.parse(req.getParameter("startDate"); 
pst.setDate(1,startDate);

You'll need to change the string in the SimpleDateFormat constructor to suit your needs (the format of your date string). The above code will work for dates formatted like 2014-03-11. Your format might be different. See http://docs.oracle.com/javase/6/docs/api/java/text/SimpleDateFormat.html