【发布时间】：2015-09-17 10:46:45
【问题描述】：
我有一个包含 4 个表（球员、成就、比赛、锦标赛）的数据库。使用 JTable 显示数据。当我单击删除按钮时，我想从表中删除数据。问题是我不知道用户要修改的表的名称，所以我无法编写正确的 SQL 语句
PreparedStatement pstm = con.prepareStatement("delete * from ?");
如何获取表名？
图形界面：
public class FbGui {
private JFrame frame;
private JTable table;
/**
* Launch the application.
*/
public static void main(String[] args) {
EventQueue.invokeLater(new Runnable() {
public void run() {
try {
FbGui window = new FbGui();
window.frame.setVisible(true);
} catch (Exception e) {
e.printStackTrace();
}
}
});
}
/**
* Create the application.
*/
public FbGui() {
initialize();
}
/**
* Initialize the contents of the frame.
*/
Connection con = null;
private void initialize() {
con = FbConnect.dbConnector();
frame = new JFrame();
frame.setBounds(100, 100, 642, 422);
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.getContentPane().setLayout(null);
JScrollPane scrollPane = new JScrollPane();
scrollPane.setBounds(189, 39, 427, 120);
frame.getContentPane().add(scrollPane);
table = new JTable();
scrollPane.setViewportView(table);
JButton btnShowPlayers = new JButton("Show players");
btnShowPlayers.addActionListener(new ActionListener() {
public void actionPerformed(ActionEvent e) {
try {
PreparedStatement pstm = con.prepareStatement("select * from fbdb.players");
ResultSet rs=pstm.executeQuery();
table.setModel(buildTableModel(rs));
} catch (SQLException e1) {
// TODO Auto-generated catch block
e1.printStackTrace();
}
}
});
btnShowPlayers.setBounds(31, 36, 148, 23);
frame.getContentPane().add(btnShowPlayers);
JButton btnShowAchievements = new JButton("Show achievements");
btnShowAchievements.addActionListener(new ActionListener() {
public void actionPerformed(ActionEvent arg0) {
try {
PreparedStatement pstm = con.prepareStatement("select * from fbdb.achievements");
ResultSet rs=pstm.executeQuery();
table.setModel(buildTableModel(rs));
} catch (SQLException e1) {
// TODO Auto-generated catch block
e1.printStackTrace();
}
}
});
btnShowAchievements.setBounds(31, 70, 148, 23);
frame.getContentPane().add(btnShowAchievements);
JButton btnShowTournaments = new JButton("Show tournaments");
btnShowTournaments.addActionListener(new ActionListener() {
public void actionPerformed(ActionEvent e) {
try {
PreparedStatement pstm = con.prepareStatement("select * from fbdb.tournaments");
ResultSet rs=pstm.executeQuery();
table.setModel(buildTableModel(rs));
} catch (SQLException e1) {
// TODO Auto-generated catch block
e1.printStackTrace();
}
}
});
btnShowTournaments.setBounds(31, 104, 148, 23);
frame.getContentPane().add(btnShowTournaments);
JButton btnShowMatches = new JButton("Show matches");
btnShowMatches.addActionListener(new ActionListener() {
public void actionPerformed(ActionEvent e) {
try {
PreparedStatement pstm = con.prepareStatement("select * from fbdb.matches");
ResultSet rs=pstm.executeQuery();
table.setModel(buildTableModel(rs));
} catch (SQLException e1) {
// TODO Auto-generated catch block
e1.printStackTrace();
}
}
});
btnShowMatches.setBounds(31, 136, 148, 23);
frame.getContentPane().add(btnShowMatches);
JButton btnDelete = new JButton("Delete");
btnDelete.addActionListener(new ActionListener() {
public void actionPerformed(ActionEvent e) {
try {
PreparedStatement pstm = con.prepareStatement("delete * from ?");
pstm.execute();
} catch (SQLException e1) {
// TODO Auto-generated catch block
e1.printStackTrace();
}
}
});
btnDelete.setBounds(208, 181, 89, 23);
frame.getContentPane().add(btnDelete);
}
public static DefaultTableModel buildTableModel(ResultSet rs)
throws SQLException {
ResultSetMetaData metaData = rs.getMetaData();
// names of columns
Vector<String> columnNames = new Vector<String>();
int columnCount = metaData.getColumnCount();
for (int column = 1; column <= columnCount; column++) {
columnNames.add(metaData.getColumnName(column));
}
// data of the table
Vector<Vector<Object>> data = new Vector<Vector<Object>>();
while (rs.next()) {
Vector<Object> vector = new Vector<Object>();
for (int columnIndex = 1; columnIndex <= columnCount; columnIndex++) {
vector.add(rs.getObject(columnIndex));
}
data.add(vector);
}
return new DefaultTableModel(data, columnNames);
}
}
【问题讨论】：
-
你的问题有点混乱。当您在代码中查询它们时，您 拥有 表名。你想删除所有四个表吗？还是您希望用户选择要删除的特定表？
-
@CraigOtis 特定表
-
您可以使用 var 来存储 JTable 中显示的数据类型。在您的删除语句中，您可以测试这个 var 以了解您必须查询的表。
-
删除按钮旁边的下拉菜单怎么样？
-
我从代码中了解到：一个 jtable，许多按钮“显示球员”，“显示比赛”（...），它们提供相同的 jtable。和一个删除按钮。问题是 rokky 从不存储 jtable 中显示的数据类型。