使用javafx从接口直接从数据库中删除数据

Question

当我选择通过ID值将其删除的数据时，我想直接从GUI中直接从TableView中删除数据，它显示错误，提示我强制转换为键入 StudentData 或同时创建一个ObservableList他们中的不起作用。我在做什么错了？

    public void Delete(ActionEvent event)
{
    try
    {
        Connection conn = SqliteConnection.Connector();
        StudentData data = (StudentData) studenttable.getSelectionModel().getSelectedItems();
        PreparedStatement ps = conn.prepareStatement("DELETE FROM Studentlist WHERE ID =?;");

        ps.setString(1, data.getID());
        ps.executeUpdate();
    }
    catch (SQLException e) {
        e.printStackTrace();
    }
}

我尝试了上面的代码，但是仍然没有结果不能删除我从GUI中选择的行

Answer 1

假设ID列为数字类型，例如整数，则应将数字Java类型绑定到?占位符，例如

Connection conn = SqliteConnection.Connector();
StudentData data = (StudentData) studenttable.getSelectionModel().getSelectedItems();
PreparedStatement ps = conn.prepareStatement("DELETE FROM Studentlist WHERE ID = ?");
ps.setInt(1, data.getID());
ps.executeUpdate();

如果data.getID()返回String，则使用以下方法将其解析为整数：

int theID = Integer.valueOf(data.getID());

，然后将其绑定到您的语句：

ps.setInt(1, theID);

请注意，从JDBC进行调用时，无需在delete语句的末尾添加分号。

Answer 2

public void Delete(ActionEvent event)
{
    try
    {
        Connection conn = SqliteConnection.Connector();
        PreparedStatement ps = conn.prepareStatement("DELETE FROM Studentlist WHERE ID = ?");
        StudentData studentdata = studenttable.getSelectionModel().getSelectedItem();
        ps.setString(1, studentdata.getID());

        ps.execute();
        conn.close();
    }
    catch (SQLException e)
    {
        System.out.println(e);
    }
}

我的猜测是

您的数据模型类名称为 StudentData

您的TableView名称为可学习

所以...语法是...

//to select tableview row
StudentData selectedrow = studenttable.getSelectionModel().getSelectedItem();

//prepare query with blank ID to be filled with the value of the selected row
PreparedStatement ps = conn.prepareStatement("DELETE FROM Studentlist WHERE ID = ?");

//from the selected row getID only
ps.setString(1, selectedrow.getID());

//execute delete operation e.g DELETE FROM Studentlist WHERE ID = 123
ps.execute();

请注意，TableView必须将StudentData作为类型参数，以避免强制转换：

@FXML
private TableView<StudentData> studenttable;