mysql - 内连接查询 - 3 个表

Question

我正在尝试执行此查询以打印三个表中的数据。但不知何故，查询没有被执行。

SELECT l.locality_id, c.city_name, l.locality_name, cloud_site_location_outlet_localities.minimum_order, cloud_site_location_outlet_localities.delivery_time, cloud_site_location_outlet_localities.delivery_charge FROM `cloud_site_location_localities` l INNER JOIN `cloud_site_location_cities` c on l.city_id=c.city_id

执行上述查询时遇到的错误是:

1054 - Unknown column 'cloud_site_location_outlet_localities.minimum_order' in 'field list'

但是，当我必须仅显示两个表中的数据时，此查询运行良好。

SELECT l.locality_id, c.city_name, l.locality_name FROM `cloud_site_location_localities` l INNER JOIN `cloud_site_location_cities` c on l.city_id=c.city_id

我哪里出错了？

当我使用以下查询将其导出为 CSV 时，我得到了冗余数据。在 1000 个条目中，我只得到了 400 个，然后这 400 个被重复。

这是我正在实现的代码

$sql = "SELECT l.locality_id, c.city_name, l.locality_name, o.minimum_order, o.delivery_time, o.delivery_charge FROM `cloud_site_location_localities` l INNER JOIN `cloud_site_location_cities` c ON l.city_id = c.city_id INNER JOIN `cloud_site_location_outlet_localities` o ON l.locality_id = o.locality_id";
$result = $DB->query($sql);


//$output = fopen($filename, 'c+');
$output = fopen('php://output', 'c+');
fputcsv($output, array('Location Id', 'City Name', 'Location Name','Minimum Order Amount','Delivery Time','Delivery Charge'));
$row = array();
$csv_output = "";
$csv_output .= "Locality Id,City Name,Locality Name,Minimum Order Amount,Delivery Time,Delivery Charge\n";
foreach($result as $locality_value)
{
    $row['locality_id'] =   $locality_value->locality_id;
    $row['city_name']       =       $locality_value->city_name;
    $row['locality_name']   =   $locality_value->locality_name;
    $row['minimum_order']   =   $locality_value->minimum_order;
    $row['delivery_time']   =   $locality_value->delivery_time;
    $row['delivery_charge'] =   $locality_value->delivery_charge;
    $csv_output .= trim($row['locality_id']).",".trim($row['city_name']).",".trim($row['locality_name']).",".trim($row['minimum_order']).",".trim($row['delivery_time']).",".trim($row['delivery_charge']).",,\n";
    fputcsv($output, $row);

}
fclose($output);
print $csv_output;

Answer 1

您缺少 cloud_site_location_outlet_localities 的 join 子句。例如:

SELECT      l.locality_id, 
            c.city_name, 
            l.locality_name, 
            o.minimum_order, 
            o.delivery_time, 
            o.delivery_charge 
FROM       `cloud_site_location_localities` l 
INNER JOIN `cloud_site_location_cities` c 
        ON l.city_id = c.city_id
INNER JOIN `cloud_site_location_outlet_localities` o 
        ON l.outlet_id = c.outlet_id --just guessing the column names