如果没有数据，如何选择NULL；如果存在，如何显示数据? [英] How to select NULL if there are no data and display the data if it exist?

问题描述

我想从MySQL数据库中选择AS NULL.这是选择查询:

I'd like to do a select AS NULL from MySQL db. This is the select query:

function get_new()
{
    $query = "SELECT DATE_FORMAT(curdate(),'%d/%m-%Y') AS date_created, NULL AS name, NULL AS address, NULL AS status FROM t_penomoran";
    $result = $this->db->query($query)->row();

    return $result;
}

这是控制器

public function add()
{
    $id         = 0;
    $master     = $this->MPenomoran->get_new();

    $data = array (
        'titlepage'     => APP_TITLEPAGE,
        'titleapp'      => 'Penomoran',
        'userid'        => $this->session->userdata('nip'),
        'id'            => $id,
        'record'        => $master,
        'error'         => '',
        'complete'      => 'true',
        'loadmethod'    => 'add',
        'contentpage'   => 'penomoran/detail');

    $this->load->view('shared/master_app', $data);
}

当我在视图上使用它时:

And when I use this on the view:

<?php echo $record->name; ?>

我很高兴得到Trying to get property of non-object error.该如何解决?

I kepp getting Trying to get property of non-object error. How to solve this?

我的表结构:

CREATE TABLE `t_penomoran` (
`nomor` int(50) NOT NULL,
`date_created` date DEFAULT NULL,
`name` varchar(100) DEFAULT NULL,
`jenis_pekerjaan` text,
`nominal` bigint(20) DEFAULT NULL,
`address` varchar(50) DEFAULT NULL,
`pic` varchar(100) DEFAULT NULL,
`keterangan` varchar(255) DEFAULT NULL,
`status` int(11) DEFAULT NULL
) ENGINE=InnoDB DEFAULT CHARSET=latin

推荐答案

如果表为空(0行)，则查询结果= null通常为

If table is empty (0 rows), the query result = null is normally.

要在存在行ID x时显示行数据，应选择列而不是select NULL AS column，因为如果存在行数据，则所有列的值永远为空.

And you want to show row data when row ID x is exists, you should be select column, not select NULL AS column, because if row data is exists, all column value is null forever.

因此，将代码更改为SQL时不要选择null，并且当查询结果为空时，将返回默认设置，如下所示:

So, change code to SQL do not select null, and when query result is empty, return a default sets, like this:

function get_data( $id )
{
    $query = "SELECT
            DATE_FORMAT(curdate(),'%d/%m-%Y') AS date_created,
            `name`,
            `address`,
            `status`
        FROM `t_penomoran`
        WHERE `nomor` = '{$id}'";

    $result = $this->db->query($query)->row();

    if ( empty($result) ) {
        $result = (object)[
            'date_created' => date('d/m-Y'),
            'name' => null,
            'address' => null,
            'status' => null,
        ];
    }

    return $result;
}

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