Question

我一直在使用mySQL，但到目前为止还没有真正想要这么高效。我目前有以下代码：

SELECT `page_name` AS manufacturer_name
FROM `manufacturers`
WHERE `id` = '$manufacturers_id'
UNION ALL
SELECT `page_name` AS series_name
FROM `series`
WHERE `id` = '$series_id'

不幸的是，这不是我想要的，它是为我选择正确的信息，但它只是在一个列名称：manufacturer_name。如何修改此选项以分别从制造商和系列中选择页面名称？这是我得到的当前输出：

manufacturer_name
my_manufacturer_name
my_series_name

这就是我想要的输出（注意：我只是将它用作列分隔符：|）：

   manufacturer_name | series_name
my_manufacturer name | my_series_name

Answer 1

如果您的结果只包含单行，请使用

select 
(
  SELECT `page_name` AS manufacturer_name
  FROM `manufacturers`
  WHERE `id` = '$manufacturers_id'
) as manufacturer_name,
(
  SELECT `page_name` AS series_name
  FROM `series`
  WHERE `id` = '$series_id'
) as series_name

UNION的另一种可能性是

SELECT `page_name` AS manufacturer_name, null as series_name
FROM `manufacturers`
WHERE `id` = '$manufacturers_id'
UNION ALL
SELECT null, `page_name`
FROM `series`
WHERE `id` = '$series_id'

但这会返回2行。

使用“分隔条件”从多个表中选择多个列

1 个答案: