我是java新手，我面临一个小问题。实际上，我正在从包含 7345987 条记录的表中提取数据并将它们显示到jtable. 到现在为止，我已经通过使用Limitand成功完成了offset。
我的查询是：
ResultSet rs1 = stmt1.executeQuery(
"SELECT ANUMBER,BNUMBER,DATETIME FROM CDR LIMIT '" + recordPerPage + "' OFFSET '" + offSet + "' ");
我已将第 1 页设置recordPerPage为 100000 和offset0，对于第 2 页，我将其offset增加到 100001，依此类推....
但我想order by按列得到结果DATETIME。当我尝试order by在我的查询中使用之前limit and offset。它需要大量时间，因为首先它order by是整个表，然后适用limit and offset于从页面到页面的每次迭代。
但我在这里想要的是它应该使用 order by 一次，然后对该结果集应用限制和偏移量。这种情况有什么解决方案吗？
这是我理解我在做什么的完整代码。
public class Try {
static Connection conn;
static JPanel panel;
static DefaultTableModel model = new DefaultTableModel();
static JTable table = new JTable(model);
static JButton fButton, lButton, pButton, nButton;
static int buttonID;
static int totalRows;
static int recordPerPage = 100;
static int totalPages = 0;
static int offSet = 0;
static String x = "", y = "", z = "", inputValue = "";
static int currentPage = 1;
static JTextField pagingInput;
private static JPanel contentPane;
/**
* Launch the application.
*/
public static void main(String[] args) {
EventQueue.invokeLater(new Runnable() {
public void run() {
try {
createAndShowGUI();
} catch (SQLException e) {
e.printStackTrace();
}
}
});
}
protected static void createAndShowGUI() throws SQLException {
JFrame frame = new JFrame();
frame.setVisible(true);
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.setBounds(30, 50, 1300, 600);
contentPane = new JPanel();
contentPane.setBorder(new EmptyBorder(5, 5, 5, 5));
contentPane.setLayout(new BorderLayout(0, 0));
frame.setContentPane(contentPane);
UIManager.put("TabbedPane.selected", Color.lightGray);
JTabbedPane tabbedPane = new JTabbedPane();
tabbedPane.setBorder(new EmptyBorder(10, 10, 10, 10));
frame.add(tabbedPane);
panel = new JPanel();
tabbedPane.addTab("TABLE", null, panel, null);
tabbedPane.setFont(new Font("Dialog", Font.BOLD | Font.ITALIC, 16));
panel.setBackground(Color.white);
panel.setLayout(new BoxLayout(panel, BoxLayout.Y_AXIS));
JPanel panel_1 = new JPanel();
tabbedPane.addTab("GRAPH", null, panel_1, null);
panel_1.setBackground(Color.white);
JTable table = new JTable();
panel.add(table);
table.setFillsViewportHeight(true);
createDBConnection();
}
private static void createDBConnection() throws SQLException {
try {
Class.forName("org.h2.Driver");
} catch (ClassNotFoundException e) {
e.printStackTrace();
}
try {
conn = DriverManager.getConnection("jdbc:h2:file:G:/hs_data/h2_db/test", "sa", "sa");
} catch (SQLException e) {
System.out.println("Unable to make connection with DB");
e.printStackTrace();
}
createPaginationButtons(conn);
}
private static void createPaginationButtons(Connection conn) throws SQLException {
Statement stmt = conn.createStatement();
ResultSet rs = stmt.executeQuery("SELECT count(*) FROM cdr");
while (rs.next()) {
totalRows = rs.getInt(1);
}
// int v = totalRows % recordPerPage == 0 ? 0 : 1;
totalPages = totalRows / recordPerPage;
createButton(totalPages);
}
private static void createButton(int totalPages) throws SQLException {
fButton = new JButton("FIRST");
lButton = new JButton("LAST");
pButton = new JButton("PREVIOUS");
nButton = new JButton("NEXT");
pagingInput = new JTextField(10);
Font bigFont = pagingInput.getFont().deriveFont(Font.PLAIN, 17f);
pagingInput.setFont(bigFont);
fButton.addActionListener(buttonlistener);
lButton.addActionListener(buttonlistener);
pButton.addActionListener(buttonlistener);
nButton.addActionListener(buttonlistener);
pagingInput.addActionListener(inputlistener);
fButton.setBackground(new Color(26, 82, 118));
lButton.setBackground(new Color(26, 82, 118));
pButton.setBackground(new Color(26, 82, 118));
nButton.setBackground(new Color(26, 82, 118));
fButton.setForeground(Color.white);
lButton.setForeground(Color.white);
pButton.setForeground(Color.white);
nButton.setForeground(Color.white);
fButton.setEnabled(false);
pButton.setEnabled(false);
JPanel buttonPanel = new JPanel();
buttonPanel.add(fButton);
buttonPanel.add(pButton);
buttonPanel.add(pagingInput);
buttonPanel.add(nButton);
buttonPanel.add(lButton);
panel.add(buttonPanel);
createTable(offSet);
}
static ActionListener inputlistener = new ActionListener() {
public void actionPerformed(ActionEvent e) {
inputValue = pagingInput.getText();
try {
buttonID = Integer.parseInt(inputValue);
offSet = (buttonID * recordPerPage) + 1;
currentPage = buttonID;
populateTable(offSet);
} catch (NumberFormatException e2) {
JOptionPane.showMessageDialog(null, "Please Enter Only Integers From 1 to'" + totalPages + "'");
// e2.printStackTrace();
} catch (SQLException e1) {
e1.printStackTrace();
}
}
};
static ActionListener buttonlistener = new ActionListener() {
public void actionPerformed(ActionEvent e) {
if (e.getSource() instanceof JButton) {
String text = ((JButton) e.getSource()).getText();
if (text == "FIRST") {
offSet = 0;
currentPage = 1;
} else if (text == "LAST") {
offSet = (totalPages * recordPerPage) + 1;
currentPage = totalPages;
} else if (text == "NEXT") {
offSet = (currentPage * recordPerPage) + 1;
currentPage++;
} else if (text == "PREVIOUS") {
if (currentPage == 2) {
offSet = 0;
currentPage--;
} else {
offSet = offSet - recordPerPage;
currentPage--;
}
}
if (currentPage >= totalPages) {
fButton.setEnabled(true);
pButton.setEnabled(true);
lButton.setEnabled(false);
nButton.setEnabled(false);
}
if (currentPage <= 1) {
fButton.setEnabled(false);
pButton.setEnabled(false);
}
if (currentPage > 1) {
fButton.setEnabled(true);
pButton.setEnabled(true);
}
try {
populateTable(offSet);
} catch (SQLException e1) {
e1.printStackTrace();
}
}
}
};
private static void createTable(int offSet) throws SQLException {
model.addColumn("ANUMBER");
model.addColumn("BNUMBER");
model.addColumn("DATETIME");
DefaultTableCellRenderer headerRenderer = new DefaultTableCellRenderer();
headerRenderer.setBackground(new Color(26, 82, 118));
headerRenderer.setForeground(Color.white);
for (int i = 0; i < table.getModel().getColumnCount(); i++) {
table.getColumnModel().getColumn(i).setHeaderRenderer(headerRenderer);
}
table.getTableHeader().setPreferredSize(new Dimension(30, 30));
UIDefaults defaults = UIManager.getLookAndFeelDefaults();
if (defaults.get("Table.alternateRowColor") == null)
defaults.put("Table.alternateRowColor", new Color(240, 240, 240));
panel.add(new JScrollPane(table));
populateTable(offSet);
}
public static void populateTable(int offSet2) throws SQLException {
model.setRowCount(0);
Statement stmt1 = conn.createStatement();
ResultSet rs1 = stmt1.executeQuery(
"SELECT ANUMBER,BNUMBER,DATETIME FROM CDR LIMIT '" + recordPerPage + "' OFFSET '" + offSet + "' ");
while (rs1.next()) {
x = rs1.getString("ANUMBER");
y = rs1.getString("BNUMBER");
z = rs1.getString("DATETIME");
model.addRow(new Object[] { x, y, z });
}
table.setRowHeight(25);
}
}