SELECT id, subject
FROM pages AS a
INNER JOIN articles AS b ON a.subject = b.id
WHERE a.id = ?
It doesn't work, it says:
General error: 1 ambiguous column name: id.
But I made an alias of table pages (a) and used it in the WHERE clause. Why is it ambiguous then?
Table pages has id, subject and some other columns. The subject column should link to the id column of another table, articles
You need to use alias before your column names, try to add them
SELECT a.id, a.subject
FROM pages AS a
INNER JOIN articles AS b
ON a.subject = b.id
WHERE a.id = ?
Note that using a.id you will get id column from table pages, if you want to get id from table articles just change to b.id