Column 'user_id' in field list is ambiguous

Question

I am attempting to get the user information of the user who left this review.

With the following code:

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:

Column 'user_id' in field list is ambiguous

What does this mean?

Answer 1

It means that both tables in the query have the column user_id.

You need to specify which one you want to get in the SELECT statement like SELECT username, image, re.user_id

Answer 2

column user_id is in both table_reviews, table_users tables.

You need to specify columns with table alias name also.

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

Answer 3

It means column user_id is in both tables ie, in table_reviews, table_users

Try like this:

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