如何从左侧外部联接中查找具有AND条件的完全匹配项

Question

I have a MySQL table
Booktable

+--------+-------------+-----+  
| bookno | bookname    | ... |  
+--------+-------------+-----+  
| 1      | FINALFANTASY| ... |  
+--------+-------------+-----+  

Authortable

+--------+-------------+-----+  
| bookno | Authorname  | ... |  
+--------+-------------+-----+  
| 1      | SQUARE      | ... |  
+--------+-------------+-----+  
| 1      | ENIX        | ... |  
+--------+-------------+-----+  

so I would like to make a search condition to get the book that match with the result.

I try with

select b.bookname,a.authorname from booktable as b 
left outer join authortable a on b.bookno = a.bookno
where a.authorname = "square" and a.authorname = "enix"

It only work with only one where condition.but when I try with two authorname there is no result found. what should I do ?

(this query it working with "OR" but not "AND" but I really want the value that match the search condition or if there are some search condition that not match but not blank it should not be showing(so or it not working in this case)

Answer 1

Use aggregation to identify which books have both the authors you want:

SELECT t1.bookname,
       t2.authorname
FROM booktable t1
INNER JOIN authortable t2
    ON t1.bookno = t2.bookno
INNER JOIN
(
    SELECT bookno
    FROM authortable
    WHERE authorname IN ('square', 'enix')
    GROUP BY bookno
    HAVING COUNT(DISTINCT authorname) = 2
) t3
    ON t1.bookno = t3.bookno

Demo here:

SQLFiddle

Answer 2

Tim Biegeleisen's answer is great, but in case you need exactly match, the the last SQL in the following is correct:

SELECT * FROM book;
SELECT * FROM author;

/* this SQL will return book's author name more than 2 also true */
SELECT b.bookname, a.authorname
FROM book AS b
JOIN author AS a ON b.bookno = a.bookno
JOIN (
  SELECT bookno FROM author
  WHERE authorname in ('SQUARE', 'ENIX')
  GROUP BY 1
  HAVING count(*) = 2
) AS a2 ON b.bookno = a2.bookno;

/* this sQL will return only 2 and all matched authors: */
SELECT b.bookname, a.authorname
FROM book AS b
JOIN author AS a ON b.bookno = a.bookno
JOIN (
  SELECT bookno FROM author
  WHERE authorname in ('SQUARE', 'ENIX')
  GROUP BY 1
  HAVING count(*) = 2
) AS a2 ON b.bookno = a2.bookno
JOIN (
  SELECT bookno FROM author 
  GROUP BY 1 
  HAVING count(distinct authorname) = 2
) AS a3 ON b.bookno = a3.bookno

PS1 - no need left join

PS2 - no need count distinct - unless your author table not design properly

If title is FANTASY genre is Adventure,fantasy, and search condition is

[ADVENTURE] = found

[FANTASY] = found

[ADVENTURE,FANTASY] = found

[ADVENTURE,FANTASY,ACTION] = not found

Then the SQL will be:

SELECT b.bookname, a.authorname
FROM book AS b
JOIN author AS a ON b.bookno = a.bookno
JOIN author AS a1 ON b.bookno = a1.bookno AND a1.authorname = 'SQUARE'
JOIN author AS a2 ON b.bookno = a2.bookno AND a2.authorname = 'ENIX'

Above is working, and I m wondering if there is a performance improvement