下面，我有一个html页面，用户在字段中输入值。然后，这些字段将转到servlet，该servlet将这些值插入到数据库中 - 其中表称为“monthly_timesheet”。如您所见，html中的两个输入字段要求用户输入“年假”和“病假”。我有另一个表“leave_remaining”（未在下面显示），其中包含名为“剩余病假”和“剩余年假”的字段。我想要的是，当执行下面的servlet时，例如用户在“年假”字段中输入“5”。我希望另一个表“leave_remaining”扣除5个年叶并更新该表。帮助表示感谢，谢谢！
TimeSheet.html
<!DOCTYPE html>
<html>
<head>
<meta charset = "UTF-8">
<link rel = "stylesheet" type = "text/css" href = "main.css">
<link rel = "stylesheet" type = "text/css" href = "sidebar.css">
<title>Maintain Time Sheet</title>
<style>
table { border-collapse: collapse; width: 50%; } th, td { text-align: left; padding: 8px; } tr:nth-child(even){background-color: #f2f2f2}
tr:hover {background-color: #e2f4ff;}
</style>
</head>
<body>
<ul>
<li><a href="PersonalInfoOutput">View Personal Information</a></li>
<li><a href="ExpenseClaim.html">View Expense Claims</a></li>
<li><a href=asdasd>View Payslips</a></li>
<li><a href="changePassAdmin.html">Change Password</a></li>
<li><a href="manageEmployee.html">Maintain Employee Information</a></li>
<li><a href=asdasdasd>Maintain Tax Information</a></li>
<li><a href=asdasd>Maintain Payroll Items</a></li>
<li><a class=active>Maintain Timesheet</a></li>
<li><a href=asda>Maintain Employee Expenses</a></li>
<li><a href=asda>Run Payroll</a></li>
<li><a href=asdasds>Generate Reports</a></li>
</ul>
<div style=margin-left:25%;padding:1px;>
</div>
<div id="container">
<h1>Maintain Time Sheet</h1>
<form action ="TimeSheetDB" method = "post">
<table border ="1">
<tr>
<td>Employee ID: </td>
<td><input type = "text" name = "employee_id" pattern="[0-9]{4}" title="4 digit number: e.g. 1234" maxlength="4" required></td>
</tr>
<tr>
<td>Hours Worked: </td>
<td><input type = "number" name = "HoursWorked" min="0" step="0.01" required></td>
</tr>
<tr>
<td>Date: </td>
<td><input type = "date" name = "date" required></td>
</tr>
<tr>
<td>Annual Leaves Taken: </td>
<td><input type = "number" min="0" name = "ALeave" required></td>
</tr>
<tr>
<td>Sick Leaves Taken: </td>
<td><input type = "number" min="0" name = "SLeave" required></td>
</tr>
</table>
<br>
<br>
<input type = "submit" value = "Submit">
</form>
</div>
</body>
</html>
TimeSheetDB.java
import java.io.*;
import javax.servlet.*;
import javax.servlet.http.*;
import java.sql.*;
public class TimeSheetDB extends HttpServlet {
protected void processRequest(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
response.setContentType("text/html;charset=UTF-8");
PrintWriter out = response.getWriter();
String employee_id = request.getParameter("employee_id");
String hours = request.getParameter("HoursWorked");
String date = request.getParameter("date");
String ALeave = request.getParameter("ALeave");
String SLeave = request.getParameter("SLeave");
try {
Class.forName("com.mysql.jdbc.Driver").newInstance();
Connection con = DriverManager.getConnection("jdbc:mysql://localhost:3306/payroll_system", "root", "");
PreparedStatement ps = con.prepareStatement("INSERT INTO payroll_system.monthly_timesheet(employeeID, Date, Hours, AnnualLeave, SickLeave) values (?,?,?,?,?)");
ps.setString(1, employee_id);
ps.setString(2, date);
ps.setString(3, hours);
ps.setString(4, ALeave);
ps.setString(5, SLeave);
int count = ps.executeUpdate();
if(count>0) {
***//this is where I want the other table to deduct the annual/sick leave balance from its columns "sick leave remaining" and annual leave remaining"//***
out.println("Details Successfully Submitted");
RequestDispatcher rs = request.getRequestDispatcher("TimeSheet.html");
rs.include(request, response);
}
}catch(Exception e)
{
e.printStackTrace();
out.println("Failed to submit details");
RequestDispatcher rs = request.getRequestDispatcher("TimeSheet.html");
rs.include(request, response);
}
out.close();
}
@Override
protected void doPost(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
processRequest(request, response);
}
@Override
protected void doGet(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
processRequest(request, response);
}
}
答案 0 :(得分：0)
你在这里看到的本质上是一个事务，你插入一个表并更新另一个表，所以你就是这样做的，添加一个新的方法，比如insertUpdateLeaves（），它接受参数，所以它会是
之类的东西public int insertUpdateLeaves(String employeeId,String date,String hours,String aLeave, String sLeave)
{
Class.forName("com.mysql.jdbc.Driver").newInstance();
Connection con = DriverManager.getConnection("jdbc:mysql://localhost:3306/payroll_system", "root", "");
con.setAutoCommit(false);
//When you set the autoCommit to false, it means no SQL statement is committed, unless you call it explicitly.
// Make two Prepared Statements one for Insert and another for Update
PreparedStatement ps = con.prepareStatement("INSERT INTO payroll_system.monthly_timesheet(employeeID, Date, Hours, AnnualLeave, SickLeave) values (?,?,?,?,?)");
String updateLeaveSQL=""; //Your Update query would be here
PreparedStatement ps1 = con.prepareStatement(updateLeaveSQL);
//First run your insert statement
ps.setString(1, employee_id);
ps.setString(2, date);
ps.setString(3, hours);
ps.setString(4, ALeave);
ps.setString(5, SLeave);
int count = ps.executeUpdate();
//Since you need the existing Annual Leaves in your Leave_Remaining table, use a select Query to get the existing ones
int existingAnnualLeaves=<Value you get from Leave_Remaining Table>;
//Now update with existing Leaves
existingAnnualLeaves=existingAnnualLeaves-ALeave;
//Run your update Query setting existingAnnualLeaves with this value
//Once you are finished with both insert and update call autoCommit.
con.commit();
);
}