Question

如果用户输入添加或删除，我尝试更新我的股票价值。

我的代码在添加和删除后运行，但会使用附加值进行更新。

我的更新只运行SQL。我尝试创建另一个preparedstatement但它没有用。代码如下，我使用的是java Netbeans。

private void Update_btnActionPerformed(java.awt.event.ActionEvent evt) {

    if (txt_add.getText().equals("") && txt_delete.getText().equals("")) {
        JOptionPane.showMessageDialog(null, "Enter Stock value");
    } else {
        String url = "jdbc:sqlserver://localhost:1433;databaseName=InventoryTrackdb";
        String un = "sa";
        String pass = "123";
        PreparedStatement pst = null;
        Connection conn = null;

        try {
            conn = DriverManager.getConnection(url, un, pass);

            int pv = Integer.parseInt((Table_stock.getValueAt(Table_stock.getSelectedRow(), 3).toString()));
            int value;
            int value1;
            if (txt_add.getText().equals("")) {
                value = 0;
            } else {
                value = Integer.parseInt(txt_add.getText());
            }
            if (txt_delete.getText().equals("")) {
                value1 = 0;
            } else {
                value1 = Integer.parseInt(txt_delete.getText());
            }
            int fv = pv + value;
            int fv1 = pv - value1;
            if (fv1 < 0) {
                JOptionPane.showMessageDialog(null, "Negative Stock");
                clear_text();
            }

            else {

                String sql = "Update  Add_item set Stock = '" + fv + "'  where Itemcode = '" + txt_id.getText()
                        + "' and Itemname = '" + txt_name.getText() + "' ";

                String sql1 = "Update  Add_item set Stock = '" + fv1 + "'  where Itemcode = '" + txt_id.getText()
                        + "' and Itemname = '" + txt_name.getText() + "' ";

                pst = conn.prepareStatement(sql1);

                pst.executeUpdate();

                pst = conn.prepareStatement(sql);

                pst.executeUpdate();

                update_table();
                JOptionPane.showMessageDialog(null, "Updated Successfully");
                clear_text();
            }
        }
        catch (SQLException ex) {
            Logger.getLogger(Main_stock.class.getName()).log(Level.SEVERE, null, ex);
        }
    }

}

以下是该页面的图片：

Answer 1

您必须使用PreparedStatement来避免语法错误或SQL注入，在您的情况下，最好还使用批处理，如下所示：

String sql = "Update  Add_item set Stock = ?  where Itemcode = ? and Itemname = ?";
try (PreparedStatement pstmt = connection.prepareStatement(sql);) {

    pstmt.setString(1, fv);
    pstmt.setString(2, txt_id.getText());
    pstmt.addBatch();//First Batch

    pstmt.setString(1, fv1);
    pstmt.setString(2, txt_id.getText());
    pstmt.addBatch();//Second batch

    int[] result = pstmt.executeBatch();//Submits both batch of commands to the database

}

如何用一个按钮运行两个更新语句？

1 个答案: