我正在使用关于数据库编程的视频课程，当前课程使用Java连接到MySQL。我已经关注了视频，甚至为这个特定问题复制了文本工作文件（所以我知道代码有效），但我仍然收到错误。该数据库用于存储书籍信息：isbn，title，author，publisher和price。我使用命令行插入完全相同的数据，但是当我使用程序进行GUI时，我收到“数据截断”错误。我知道“数据截断”错误有多个答案;但是，我没有看到数据太大的地方，特别是在使用非GUI界面插入工作时。除价格为FLOAT外，所有数据类型均为VARCHAR。我得到的错误是：
插入书籍值（'978007106789'，'Stuck On Java'，'J Reid'，'9.99'，'Osborne'） 执行SQL时出错 java.sql.SQLException：第1行的“price”列截断数据
GUI代码是：
package Connection;
import java.awt.*;
import java.awt.event.*;
import javax.swing.*;
import java.sql.*;
import java.util.*;
public class InsertRecord extends JFrame {
private JButton getBookButton, insertBookButton;
private JList bookList;
private Connection connection;
private JTextField isbn, title, author, price, publisher;
private JTextArea errorText;
public InsertRecord() {
try {
Class.forName("com.mysql.jdbc.Driver").newInstance();
}
catch (Exception e) {
System.err.println("Unable to load driver.");
System.exit(1);
}
}
public void loadBook() {
Vector<String> v = new Vector<String>();
try {
Statement statement = connection.createStatement();
ResultSet rs = statement.executeQuery("select title from book");
while (rs.next()) {
v.addElement(rs.getString("title"));
}
rs.close();
}
catch (SQLException e) {
System.err.println("Error executing SQL");
}
bookList.setListData(v);
}
private void createGUI() {
Container c = getContentPane();
c.setLayout(new FlowLayout());
bookList = new JList();
loadBook();
bookList.setVisibleRowCount(2);
JScrollPane bookListScrollPane = new JScrollPane(bookList);
getBookButton = new JButton("Get Book Title");
getBookButton.addActionListener(
new ActionListener() {
public void actionPerformed(ActionEvent e) {
String query = "select * from book where title = " +
bookList.getSelectedValue();
try {
Statement statement = connection.createStatement();
ResultSet rs = statement.executeQuery(
"select * from book where title = '"
+ bookList.getSelectedValue() + "'");
/*ResultSet rs = statement.executeQuery(
"select * from book where title = 'Java:How To Program'"); */
if (rs.next()) {
isbn.setText(rs.getString("isbn"));
title.setText(rs.getString("title"));
author.setText(rs.getString("author"));
price.setText(rs.getString("price"));
publisher.setText(rs.getString("publisher"));
}
}
catch (SQLException ex) { isbn.setText(query); }
}
}
);
insertBookButton = new JButton("Insert Book");
insertBookButton.addActionListener (
new ActionListener() {
public void actionPerformed(ActionEvent e) {
try {
Statement statement = connection.createStatement();
String insert = "insert into book values(";
insert += "'" + isbn.getText() + "',";
insert += "'" + title.getText() + "',";
insert += "'" + author.getText() + "',";
insert += "'" + price.getText() + "',";
insert += "'" + publisher.getText() + "')";
System.out.println(insert);
/*int i = statement.executeUpdate("insert into book values(" +
"'" + isbn.getText() + "'," +
"'" + title.getText() + "'," +
"'" + author.getText() + "'," +
"'" + price.getText() + "'," +
"'" + publisher.getText() + ")");*/
int i = statement.executeUpdate(insert);
errorText.append("Inserted " + i + " rows succcessfully.");
bookList.removeAll();
loadBook();
}
catch (SQLException ex) {
System.err.println("Error executing SQL");
ex.printStackTrace();
}
}
}
);
JPanel first = new JPanel(new GridLayout(3,1));
first.add(bookListScrollPane);
first.add(getBookButton);
first.add(insertBookButton);
isbn = new JTextField(13);
title = new JTextField(50);
author = new JTextField(50);
price = new JTextField(8);
publisher = new JTextField(50);
errorText = new JTextArea(5,15);
errorText.setEditable(false);
JPanel second = new JPanel();
second.setLayout(new GridLayout(6,1));
second.add(isbn);
second.add(title);
second.add(author);
second.add(price);
second.add(publisher);
JPanel third = new JPanel();
third.add(new JScrollPane(errorText));
c.add(first);
c.add(second);
c.add(third);
setSize(800, 400);
setVisible(true);
}
public void connectToDB() throws Exception {
//Connection conn = null;
try {
String userName = "jesse";
String password = "password";
String url = "jdbc:mysql://localhost/library";
Class.forName("com.mysql.jdbc.Driver").newInstance();
connection = DriverManager.getConnection(url, userName, password);
//if (conn != null) System.out.println("Database connection successful.");
}
catch (SQLException e) {
System.out.println("Can't connect to database");
System.exit(1);
}
}
private void init() throws Exception{
connectToDB();
}
public static void main(String[] args) throws Exception {
InsertRecord insert = new InsertRecord();
insert.addWindowListener(
new WindowAdapter() {
public void windowClosing(WindowEvent e) {
System.exit(0);
}
}
);
insert.init();
insert.createGUI();
}
}
简单地使用命令行的插入代码是：
package Connection;
import java.sql.*;
import java.io.*;
public class InsertDB {
Connection connection;
public InsertDB(){
try {
Class.forName("com.mysql.jdbc.Driver").newInstance();
}
catch (Exception e) {
System.out.println("Could not load driver.");
e.printStackTrace();
}
}
public void ConnectToDB() {
try {
connection = DriverManager.getConnection("jdbc:mysql://localhost/library", "jesse", "password");
System.out.println("Connected to database.");
}
catch (Exception e) {
System.out.println("Cannot connect to database.");
e.printStackTrace();
}
}
public void execSQL() {
try {
Statement stmt = connection.createStatement();
BufferedReader input = new BufferedReader(new InputStreamReader(System.in));
System.out.print("Enter the isbn: ");
String isbn = input.readLine();
System.out.print("Enter the title: ");
String title = input.readLine();
System.out.print("Enter the author: ");
String author = input.readLine();
System.out.print("Enter the publisher: ");
String pub = input.readLine();
System.out.print("Enter the price: ");
String p = input.readLine();
double price = Double.parseDouble(p);
String insert = "Insert into book values (" + "'" + isbn + "','" + title + "','" + author + "','" + pub + "'," + price + ")";
System.out.println(insert);
int inserted = stmt.executeUpdate(insert); //returns 1 for success, 0 for failure
if (inserted > 0) {
System.out.println("Successfully inserted " + inserted + " row.");
}
}
catch (Exception e) {
System.out.println("Error executing SQL");
e.printStackTrace();
}
}
public static void main(String[] args){
InsertDB conn = new InsertDB();
conn.ConnectToDB();
conn.execSQL();
}
}
我注意到的唯一区别是价格在GUI代码的引号中;但是，删除引号只会导致相同的错误没有引号。另外我注意到GUI代码将价格设置为8位（原始代码为10），而浮点数未设置为MySQL中的任何内容（我相信我在另一篇文章中读到它默认为8位...这就是为什么我用过8）。我联系了视频的作者，他建议我删除价格周围的报价。但正如我所说，这没有帮助...此代码也是从他工作的视频中复制的。任何帮助表示赞赏。
数据库代码是：
drop table book;
create table book (
isbn_13 varchar(13) primary key,
title varchar(50),
author varchar(50),
publisher varchar(50),
price float(11)
);
答案 0 :(得分：0)
从头开始我完全删除了book表，然后使用上面的MySQL代码重新创建它。重新创建表后，我可以使用GUI代码插入。我不确定我的问题的原因是什么，但丢弃和重新创建表似乎解决了它。