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我正在使用數據庫編程的視頻課程，當前課程正在使用Java連接到MySQL。我跟着視頻，甚至複製了這個特定問題的文本工作文件（所以我知道代碼工作），但我仍然收到錯誤。該數據庫用於存儲書籍的信息：標題，作者，出版商和價格。我使用命令行插入了完全相同的數據，但是當我將該程序用於GUI時，出現「數據截斷」錯誤。我知道在「數據截斷」錯誤中有多個答案;但是，我沒有看到數據太大的情況，特別是在使用非GUI界面插入作品時。所有的數據類型都是VARCHAR，除了價格是FLOAT。我得到的錯誤是：在GUI中使用FLOAT時截斷列的數據
插入到賬面價值（ '978007106789'， '粘住的Java'， 'Ĵ瑞德'， '9.99'， '奧斯本'） 錯誤執行SQL 值java.sql.SQLException：數據在行截斷爲列 '價格' 1
GUI代碼是：
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();
}
}
用於簡單地使用命令行的插入件的代碼是：
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();
}
}
唯一迪菲rences我注意到價格在GUI代碼中被引用;但是，刪除引號只會導致沒有引號的相同錯誤。另外我注意到GUI代碼將價格設置爲8位（原始代碼爲10），而float在MySQL中並未設置爲任何內容（我相信我在另一篇文章中讀到它默認是8位......這就是爲什麼我使用8）。我聯繫了視頻的作者，他建議我刪除有關價格的報價。但正如我所說的，這並沒有幫助...此代碼是從他的視頻工作文件複製的。任何幫助表示讚賞。
數據庫的代碼是：
drop table book;
create table book (
isbn_13 varchar(13) primary key,
title varchar(50),
author varchar(50),
publisher varchar(50),
price float(11)
);
你能否還請包括你使用創建表的代碼？ – npinti
放桌子書; 創建表書（ \t isbn_13 VARCHAR（13）主鍵， \t標題VARCHAR（50）， \t作者VARCHAR（50）， \t出版商VARCHAR（50），\t 價格浮子（11） ）; –
初始化文本字段時，使用無參數構造函數。當從GUI讀取時，而不是'isbn.getText（）'使用'isbn.getText（）。trim（）'。這應該刪除不必要的空白。 – npinti