Question

NetBeans是我的Java编程编辑器。我编写了以下JDBC Prepared Statements代码。代码编译得很好，但是当我运行它时会产生错误。我检查了所有的Java书籍;没有关于使用NetBeans来编写使用JDBC准备语句的应用程序的示例我需要帮助。

以下是代码：

private void editButtonActionPerformed(java.awt.event.ActionEvent evt)
{                                               
    String sql = "Update Products SET"
            + "Description = ?, "
            + "Price = ? "
            + "Where Code = ?";
    try
    {
        pstmt.setString(1, "CODE");
        pstmt.setString(2, "DESCRIPTION");
        pstmt.setDouble(3, Double.parseDouble("PRICE"));

        int rowUpdated = pstmt.executeUpdate();
        if (rowUpdated > 0)
        {
            JOptionPane.showMessageDialog(null,
                    "record updated successfully");
        }
        // Clean-up environment
        rs.close();
        pstmt.close();
        con.close();
    } catch (SQLException e)
    {
        JOptionPane.showMessageDialog(Product.this, e.getMessage());
    }
}                                          

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

}                                            

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

}                                            

private void acceptButtonActionPerformed(java.awt.event.ActionEvent evt)                                             
{                                                 
    try
    {
        String sql = "Insert into PRODUCTS(CODE, DESCRIPTION, PRICE)"
                + "Values(?, ?, ?)";
        pstmt = con.prepareStatement(sql);

        pstmt.setString(1, codeTextField.getText());
        pstmt.setString(2, descriptionTextField.getText());
        pstmt.setDouble(3, Double.parseDouble("Price"));

        int rowInserted = pstmt.executeUpdate();

        if (rowInserted > 0)
        {
            JOptionPane.showMessageDialog(
                    null, "A new user was inserted successfully!");
        }

        // Clean-up environment
        rs.close();
        pstmt.close();
        con.close();
    } catch (SQLException e)
    {
        JOptionPane.showMessageDialog(Product.this, e.getMessage());
    }

}

Answer 1

在＆＃34; SET＆＃34;

之后添加一个空格

String sql = "Update Products SET "
            + "Description = ?, "
            + "Price = ? "
            + "Where Code = ?";

并最终在＆＃34;值＆＃34;

之前的空格

String sql = "Insert into PRODUCTS(CODE, DESCRIPTION, PRICE)"
            + " Values(?, ?, ?)";

Answer 2

您的查询中存在空格问题，同时在设置值时，顺序应为Descripcion，Price和Code。像这样：

 private void editButtonActionPerformed(java.awt.event.ActionEvent evt)
 {                                               
    String sql = "Update Products SET Description = ?, Price = ? "
       + "where Code = ?";
    try
    {
        pstmt.setString(1, "DESCRIPTION");
        pstmt.setDouble(2, Double.parseDouble("PRICE"));
        pstmt.setString(3, "CODE");

        int rowUpdated = pstmt.executeUpdate();
        if (rowUpdated == 1)
        {
            JOptionPane.showMessageDialog(null,
                    "record updated successfully");
        }
        // Clean-up environment
        rs.close();
        pstmt.close();
        con.close();
    } catch (SQLException e)
    {
        JOptionPane.showMessageDialog(Product.this, e.getMessage());
    }
}

我不知道为什么这些Prepared Statements代码会生成错误

2 个答案: