MySQL Multiple Select Ambiguous Results - mysql

Question

Using phpMyAdmin 5.1.44 to experiment with DML commands.
I've been following tutorials on-line.
SELECT book.b_isbn, publisher.p_name FROM 'book', 'publisher' WHERE book.b_title='DSA'
Table 1
book
b_id(PK) b_isbn b_title p_id(FK)
-----------------------------------------
1 12345 DSA 1
2 23456 SD 1
3 34567 CSP 2
Table 2
publisher
p_id(PK) p_name
--------------------
1 Fred
2 John
Expected Results
b_isbn p_name
---------------------
12345 Fred
Actual Results
b_isbn p_name
----------------------
12345 Fred
34567 John
Any ideas?

Answer 1

You need to tell MySQL how to join the tables together (without which it just matches every book to every publisher) - use any one of:
add AND publisher.p_id = book.p_id to your WHERE clause;
tell MySQL to join ON that condition / USING that column;
... FROM book JOIN publisher ON publisher.p_id = book.p_id WHERE ...
or
... FROM book JOIN publisher USING (p_id) WHERE ...
use a NATURAL JOIN to have MySQL guess that's what you want based on the column names.
... FROM book NATURAL JOIN publisher WHERE ...

Answer 2

I think you need to put the fk to the pk key in the where statement
SELECT
*
FROM
book, publisher
WHERE
book.p_id=publisher.p_id
AND book.b_title='DSA'
Or even better use JOINs:
SELECT
*
FROM
book
JOIN publisher
ON book.p_id=publisher.p_id
WHERE
book.b_title='DSA'
Or if you are not sure if there is a corresponding value then use a left join. Like this:
SELECT
*
FROM
book
LEFT JOIN publisher
ON book.p_id=publisher.p_id
WHERE
book.b_title='DSA'