where 子句中的 City_id 不明确答案

【问题标题】：City_id in the where clause is ambiguouswhere 子句中的 City_id 不明确
【发布时间】：2013-04-14 05:14:38
【问题描述】：

我已经编写了查询，但它在 where 子句中显示的城市 ID 不明确

SELECT
  `a`.`name`,
  `a`.`company`,
  `a`.`city`,
  `a`.`country`,
  `a`.`phone`,
  `a`.`type_of_enquiry`,
  `b`.`enquiry_id`,
  `a`.`hearaboutus`,
  `a`.`email`,
  `a`.`comments`,
  `a`.`address`,
  `c`.`id`,
  `c`.`city_id`
FROM (`sobha_enquiry` a)
  LEFT JOIN `sobha_enquiryzone` b
    ON `b`.`enquiry_id` = `a`.`id`
  LEFT JOIN `sobha_admin` c
    ON `c`.`city_id` = `b`.`city_id`
WHERE `city_id` = '2'
GROUP BY `a`.`id`
ORDER BY `id` desc, `a`.`id` DESC

请帮帮我！！！！！！！！！！

【问题讨论】：

标签： mysql codeigniter codeigniter-2 codeigniter-url

【解决方案1】：

SELECT
  `a`.`name`,
  `a`.`company`,
  `a`.`city`,
  `a`.`country`,
  `a`.`phone`,
  `a`.`type_of_enquiry`,
  `b`.`enquiry_id`,
  `a`.`hearaboutus`,
  `a`.`email`,
  `a`.`comments`,
  `a`.`address`,
  `c`.`id`,
  `c`.`city_id`
FROM (`sobha_enquiry` a)
  LEFT JOIN `sobha_enquiryzone` b
    ON `b`.`enquiry_id` = `a`.`id`
  LEFT JOIN `sobha_admin` c
    ON `c`.`city_id` = `b`.`city_id`
WHERE `a`.`city_id` = '2'
GROUP BY `a`.`id`
ORDER BY `c`.`id` desc, `a`.`id` DESC

在你的 where 子句中你应该提供 b 或 c 因为使用别名并且列 city_id 存在于两个表中，这会混淆 mysql

【讨论】：

也许你的意思是b or c而不是a or c。

【解决方案2】：

问题在于WHERE 子句，您需要指定要在哪个表中搜索city_id，因为它们都包含相同的列名。它可能来自sobha_enquiryzone 或来自sobha_admin。

SELECT  a.NAME,
        a.company,
        a.city,
        a.country,
        a.phone,
        a.type_of_enquiry,
        b.enquiry_id,
        a.hearaboutus,
        a.email,
        a.comments,
        a.address,
        c.id,
        c.city_id
FROM    sobha_enquiry a
        LEFT JOIN sobha_enquiryzone b
                ON b.enquiry_id = a.id
        LEFT JOIN sobha_admin c
                ON c.city_id = b.city_id
WHERE   b.city_id = '2' -- or c.city_id = '2' (both will yield the same result)
GROUP   BY a.id
ORDER   BY id DESC, a.id DESC

【讨论】：