MySQL 字段列表中的“user_id”列不明确
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Column 'user_id' in field list is ambiguous
提问by crmepham
I am attempting to get the user information of the user who left this review.
我正在尝试获取留下此评论的用户的用户信息。
With the following code:
使用以下代码：
SELECT username, image, user_id FROM table_users AS us
JOIN table_reviews AS re
ON re.user_id = us.user_id
WHERE us.user_id = 1 AND
re.review_id= 1
I get the error:
我收到错误：
Column 'user_id' in field list is ambiguous
字段列表中的“user_id”列不明确
What does this mean?
这是什么意思？
回答by MikeSmithDev
It means that both tables in the query have the column user_id.
这意味着查询中的两个表都有列user_id。
You need to specify which one you want to get in the SELECT statement like
SELECT username, image, re.user_id
您需要在 SELECT 语句中指定要获取的内容，例如
SELECT username, image, re.user_id
回答by Praveen Prasannan
column user_id is in both table_reviews, table_userstables.
列user_id是在两个table_reviews，table_users表中。
You need to specify columns with table alias name also.
您还需要使用表别名指定列。
SELECT username, image, us.user_id FROM table_users AS us
JOIN table_reviews AS re
ON re.user_id = us.user_id
WHERE us.user_id = 1 AND
re.review_id= 1
回答by Rahul Tripathi
It means column user_id is in both tables ie, in table_reviews, table_users
这意味着列 user_id 在两个表中，即在 table_reviews, table_users
Try like this:
像这样尝试：
SELECT username, image, us.user_id //or re.user_id
FROM table_users AS us
JOIN table_reviews AS re
ON re.user_id = us.user_id
WHERE us.user_id = 1 AND
re.review_id= 1
回答by fico7489
Not only selected values(SELECT username, image, user_id) are examined in where clause (WHERE us.user_id = 1), all joined columns are examined in where clause, so in your example you have user_id column in both joined tables. If you have query like this one:
不仅在 where 子句（WHERE us.user_id = 1）中检查选定的值（SELECT username、image、user_id），在 where 子句中检查所有连接的列，因此在您的示例中，两个连接表中都有 user_id 列。如果您有这样的查询：
SELECT table_reviews.id FROM table_users AS us
JOIN table_reviews AS re
ON re.user_id = us.user_id
WHERE id
id will be ambiguous because id-s from table_reviews and table_reviews will be examined in where clause although only id from table_reviews is selected.
id 将是不明确的，因为来自 table_reviews 和 table_reviews 的 id-s 将在 where 子句中进行检查，尽管只选择了来自 table_reviews 的 id。
