数据库删除操作

Question

我想在我的数据库上执行一个简单的删除操作，但是我的程序变得繁忙并且停止响应。我不知道发生了什么，因为它没有显示错误。

private void deleteCustomer(ActionEvent event) {
    String mName = name.getText(); 
    String mID = id.getText();


    Boolean flag = mName.isEmpty() || mID.isEmpty(); 
    if(flag){
        Alert alert = new Alert(Alert.AlertType.ERROR); 
        alert.setHeaderText(null);
        alert.setContentText("Please Enter All Fields.");
        alert.showAndWait();
        return;
    }
     String st = "DELETE CUSTOMER WHERE id = '"+ mID +"'" ;
    System.out.println(st);
    if(handler.execAction(st)){
        Alert alert = new Alert(Alert.AlertType.INFORMATION); 
        alert.setHeaderText(null);
        alert.setContentText("Deleted");
        alert.showAndWait();
        //return;
    }else{
        Alert alert = new Alert(Alert.AlertType.ERROR); 
        alert.setHeaderText(null);
        alert.setContentText("Error Occured");
        alert.showAndWait();

    }
}

下面是我用来完成任务的方法

 public boolean execUpdate(String query){
    try {
        stmt = conn.createStatement();
        //stmt.executeUpdate(query);
        if(stmt.executeUpdate(query) == 1){
           // JOptionPane.showMessageDialog(null, "data " + message);
            System.out.println("data deleted succefully!!");
        }

        return true; 
    } catch (SQLException e) {
        JOptionPane.showMessageDialog(null, "error: "+ e.getMessage(), "error occoured", JOptionPane.ERROR_MESSAGE);
        System.out.println("Exception at execQuery: dataHandler" + e.getLocalizedMessage());
        return false; 
    }finally{
}


public boolean execAction(String query){
    try {
        stmt = conn.createStatement();
        stmt.execute(query);

        return true; 
    } catch (SQLException e) {
        JOptionPane.showMessageDialog(null, "error: "+ e.getMessage(), "error occoured", JOptionPane.ERROR_MESSAGE);
        System.out.println("Exception at execQuery: dataHandler" + e.getLocalizedMessage());
        return false; 
    }finally{
}
}

Answer 1

我想您忘记在SQL中添加FROM关键字了。

String st = "DELETE FROM CUSTOMER WHERE id = '"+ mID +"'" ;