Giving weight to mysql search results - mysql

Question

I'm trying to improve my search functionality in one of my sites by ordering the records by those with the most matches.
I have the following mysql tables.
SurveyResponses
+--------+-------------+------------------+
| sID | Title | Description |
+--------+-------------+------------------+
| 1 | Set 1 | Some txt here |
| 2 | Set 2 | Other text here |
+--------+-------------+------------------+
Answers:
+------+---------+------------+---------+
| aID | Parent | Question | Answer |
+------+---------+------------+---------+
| 1 | 1 | 1 | yes |
| 2 | 1 | 2 | yes |
| 3 | 1 | 3 | yes |
| 4 | 2 | 1 | yes |
| 5 | 2 | 2 | no |
| 6 | 2 | 3 | no |
+------+---------+------------+---------+
I want to get ALL the records from the SurveyResponses table and order them in order of the questions that were matched as correct in the answers table. The correct answers are as follows:
Q1 = yes
Q2 = no
Q3 = no
So based on this, the query should return Set 2 at the top of the results because the answers were all correct in the answers table for that question, whereas q2 and q3 were wrong in Set 1.
I imagine I need some kind of scoring system so I can do something like
IF q1 = yes THEN score = score + 1
Obviously I can do this in PHP, but not sure what method to use in mysql.
A answer to the question would be appreciated, but even a hint or link to the best approach would be greatly appreciated.

Answer 1

I don't really understand your design, or what you're trying to do so instead I'll offer up an alternative example that may or may not be helpful...
CREATE TABLE survey
(question_id INT NOT NULL AUTO_INCREMENT PRIMARY KEY
,question VARCHAR(100) NOT NULL UNIQUE
,correct_answer VARCHAR(3) NOT NULL
);
INSERT INTO survey VALUES
(1,'Is Rome the capital of Italy?','Yes'),
(2,'Is Paris the capital of England?','No'),
(3,'Is London the capital of Spain?','No');
CREATE TABLE survey_response
(user_id INT NOT NULL
,question_id INT NOT NULL
,response VARCHAR(3) NOT NULL
,PRIMARY KEY(user_id,question_id)
);
INSERT INTO survey_response VALUES
(101,1,'Yes'),
(101,2,'Yes'),
(101,3,'Yes'),
(102,1,'Yes'),
(102,2,'No'),
(102,3,'No');
SELECT * FROM survey;
+-------------+----------------------------------+----------------+
| question_id | question | correct_answer |
+-------------+----------------------------------+----------------+
| 1 | Is Rome the capital of Italy? | Yes |
| 2 | Is Paris the capital of England? | No |
| 3 | Is London the capital of Spain? | No |
+-------------+----------------------------------+----------------+
SELECT * FROM survey_response;
+---------+-------------+----------+
| user_id | question_id | response |
+---------+-------------+----------+
| 101 | 1 | Yes |
| 101 | 2 | Yes |
| 101 | 3 | Yes |
| 102 | 1 | Yes |
| 102 | 2 | No |
| 102 | 3 | No |
+---------+-------------+----------+
So let's say I want to sort respondents (user_ids) according to who got the most correct answers. i could do that this way...
SELECT sr.user_id
FROM survey s
JOIN survey_response sr
ON sr.question_id = s.question_id
GROUP
BY user_id
ORDER
BY SUM(sr.response = s.correct_answer) DESC;
+---------+
| user_id |
+---------+
| 102 |
| 101 |
+---------+