It came to a situation when I was required to create an SQL SELECT statement of table A. At the same time, the table primary key became a foreign key in table B. Table B had multiple entries for each foreign key from table A. Adding in to the existing SQL SELECT statement, I was required to retrieve the first row out of table B for each foreign key from table A.
I came out with this:
SELECT a.*, b.b_id, b.b_name FROM TableA AS a LEFT JOIN ( SELECT id AS b_id, a_id, name AS b_name FROM TableB GROUP BY a_id ) AS b ON a.id=b.a_id;
Amazingly, the solution worked, well, at least to retrieve an accurate information. I am still looking for a better query to work with.