删除数据使用的SQL语句为delete语句，如果删除图书id为1的图书信息，其SQL语句为：
delete from book where id=1
在实际开发中删除数据通常使用PreparedStatement对象进行操作。
实例代码：
（1）index.jsp
1 <%@ page language="java" contentType="text/html; charset=UTF-8" 2 pageEncoding="UTF-8"%> 3 <!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd"> 4 <html> 5 <head> 6 <meta http-equiv="Content-Type" content="text/html; charset=UTF-8"> 7 <title>查看所有图书</title> 8 </head> 9 <body> 10 <a href="FindServlet">查看所有图书</a> 11 </body> 12 </html>
（2）book_list.jsp
1 <%@ page language="java" contentType="text/html; charset=UTF-8" 2 pageEncoding="UTF-8"%> 3 <%@ page import="com.java.Book" %> 4 <%@ page import="java.util.ArrayList" %> 5 <%@ page import="java.util.List" %> 6 <!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd"> 7 <html> 8 <head> 9 <meta http-equiv="Content-Type" content="text/html; charset=UTF-8"> 10 <title>删除数据</title> 11 <style> 12 td{ 13 font-size:12px; 14 } 15 h2{ 16 margin:2px; 17 } 18 </style> 19 <script type="text/javascript"> 20 function check(form){ 21 with(form){ 22 if(bookCount.value == ""){ 23 alert("请输入更新数量！"); 24 return false; 25 } 26 if(isNaN(bookCount.value)){ 27 alert("格式错误！"); 28 return false; 29 } 30 return true; 31 } 32 } 33 </script> 34 </head> 35 <body> 36 <div style="text-align:center;"> 37 <table align="center" width="500px" border="1" height="170px" bordercolor="white" bgcolor="black" cellpadding="1"> 38 <tr bgcolor="white"> 39 <td align="center" colspan="6"> 40 <h2>所有图书信息 </h2> 41 </td> 42 </tr> 43 <tr align="center" bgcolor="#e1ffc1"> 44 <td><b>ID</b></td> 45 <td><b>图书名称</b></td> 46 <td><b>价格</b></td> 47 <td><b>作者</b></td> 48 <td><b>修改数量</b></td> 49 <td><b>删除</b></td> 50 </tr> 51 <% 52 List<Book> list = (List<Book>)request.getAttribute("list"); 53 if(list ==null || list.size() < 1){ 54 out.print("数据为空"); 55 }else{ 56 for(Book book:list){ 57 58 59 60 %> 61 <tr align="center" bgcolor="white"> 62 <td><%= book.getId() %></td> 63 <td><%= book.getName() %></td> 64 <td><%= book.getPrice() %></td> 65 <td><%= book.getBookCount() %></td> 66 <td><%= book.getAuthor() %></td> 67 <td> 68 <a href="DeleteServlet?id=<%=book.getId()%>">删除</a> 69 </td> 70 </tr> 71 <% 72 } 73 } 74 %> 75 </table> 76 </div> 77 </body> 78 </html>
（3）Book类
1 package com.java; 2 3 public class Book { 4 private int id; 5 private String name; 6 private double price; 7 private int bookCount; 8 private String author; 9 public int getId() { 10 return id; 11 } 12 public void setId(int id) { 13 this.id = id; 14 } 15 public String getName() { 16 return name; 17 } 18 public void setName(String name) { 19 this.name = name; 20 } 21 public double getPrice() { 22 return price; 23 } 24 public void setPrice(double price) { 25 this.price = price; 26 } 27 public int getBookCount() { 28 return bookCount; 29 } 30 public void setBookCount(int bookCount) { 31 this.bookCount = bookCount; 32 } 33 public String getAuthor() { 34 return author; 35 } 36 public void setAuthor(String author) { 37 this.author = author; 38 } 39 }
（4）FindServlet类
1 package com.java; 2 3 import java.io.IOException; 4 import java.sql.Connection; 5 import java.sql.DriverManager; 6 import java.sql.PreparedStatement; 7 import java.sql.ResultSet; 8 import java.sql.SQLException; 9 import java.util.ArrayList; 10 import java.util.List; 11 12 import javax.servlet.ServletException; 13 import javax.servlet.http.HttpServlet; 14 import javax.servlet.http.HttpServletRequest; 15 import javax.servlet.http.HttpServletResponse; 16 17 import com.java.Book; 18 19 public class FindServlet extends HttpServlet { 20 private static final long serialVersionUID = 1L; 21 private String sql = "select * from book"; 22 private String url = "jdbc:mysql://localhost:3306/test"; 23 private String username = "root"; 24 private String password = "123456"; 25 26 protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { 27 try { 28 Class.forName("com.mysql.jdbc.Driver"); 29 } catch (ClassNotFoundException e1) { 30 // TODO Auto-generated catch block 31 e1.printStackTrace(); 32 } 33 Connection conn=null; 34 try { 35 conn = DriverManager.getConnection(url,username,password); 36 } catch (SQLException e1) { 37 // TODO Auto-generated catch block 38 e1.printStackTrace(); 39 } 40 41 try { 42 PreparedStatement ps = conn.prepareStatement(sql); 43 ResultSet rs = ps.executeQuery(sql); 44 List<Book> list = (List<Book>)new ArrayList(); 45 while(rs.next()) { 46 Book book = new Book(); 47 book.setId(rs.getInt("id")); 48 book.setName(rs.getString("name")); 49 book.setPrice(rs.getDouble("price")); 50 book.setBookCount(rs.getInt("bookCount")); 51 book.setAuthor(rs.getString("author")); 52 list.add(book); 53 } 54 request.setAttribute("list",list); 55 rs.close(); 56 ps.close(); 57 conn.close(); 58 } catch (SQLException e) { 59 // TODO Auto-generated catch block 60 e.printStackTrace(); 61 } 62 63 request.getRequestDispatcher("book_list.jsp").forward(request, response); 64 } 65 }
（5）DeleteServlet类
1 package com.java; 2 3 import java.io.IOException; 4 import java.sql.Connection; 5 import java.sql.DriverManager; 6 import java.sql.PreparedStatement; 7 import java.sql.SQLException; 8 9 import javax.servlet.ServletException; 10 import javax.servlet.http.HttpServlet; 11 import javax.servlet.http.HttpServletRequest; 12 import javax.servlet.http.HttpServletResponse; 13 14 public class DeleteServlet extends HttpServlet { 15 16 private static final long serialVersionUID = 1L; 17 protected void doGet(HttpServletRequest request,HttpServletResponse response) throws IOException,ServletException{ 18 int id = Integer.valueOf(request.getParameter("id")); 19 20 try { 21 Class.forName("com.mysql.jdbc.Driver"); 22 String url = "jdbc:mysql://localhost:3306/test"; 23 String username = "root"; 24 String password = "123456"; 25 Connection conn=null; 26 try { 27 conn = DriverManager.getConnection(url,username,password); 28 } catch (SQLException e1) { 29 // TODO Auto-generated catch block 30 e1.printStackTrace(); 31 } 32 String sql = "delete from book where id=?"; 33 PreparedStatement ps; 34 try { 35 ps = conn.prepareStatement(sql); 36 ps.setInt(1, id); 37 ps.executeUpdate(); 38 ps.close(); 39 conn.close(); 40 } catch (SQLException e) { 41 // TODO Auto-generated catch block 42 e.printStackTrace(); 43 } 44 45 } catch (ClassNotFoundException e) { 46 // TODO Auto-generated catch block 47 e.printStackTrace(); 48 } 49 50 response.sendRedirect("FindServlet"); 51 52 } 53 54 55 }
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