Analyzing Survey Data with MySQL

I've got some simple survey data that I'd love to have a hand with. I work with PHP/MYSQL.

Basically, the survey has 20 questions with 3 possible answers for each: Y, N and N/A. I want to 'score' each survey at the end using the formula: Y/(Y+N).

The Question: How do I actually come up with the 'SCORE' column at the end? Using a SQL query or using PHP (somehow)? Is there some kind of COUNTIF function in MYSQL like Excel has?

A query like: COUNTIF("Y", Column1:Column20) would be awesome—if it existed!

Suggestions appreciated! (I guess I'm looking for as much procedural advice as technical with this question).

Thanks

Terry

            Q1   Q2  Q3  Q4  Q5  SCORE
            ---------------------            
Person1 -   y    n   y    n   n/a  50%
Person2 -   y    y   y    y   y    100% 
Person3 -   y    y   y    y 开发者_高级运维  n/a  100%

---

No tricks. A long winded SUM(CASE ...)

It'd be easier with one row per question... especially when you add more questions. See First Normal Form

SELECT
   SUM(
     CASE WHEN Q1 = 'y' THEN 1 ELSE 0 END +
     CASE WHEN Q2 = 'y' THEN 1 ELSE 0 END +
     ...
     CASE WHEN Q20 = 'y' THEN 1 ELSE 0 END
     )
   /
   SUM(
     CASE WHEN Q1 IN ('y', 'n') THEN 1 ELSE 0 END +
     CASE WHEN Q2 IN ('y', 'n') THEN 1 ELSE 0 END +
     ...
     CASE WHEN Q20 IN ('y', 'n') THEN 1 ELSE 0 END
     ),
   Person
FROM
   myTable
GROUP BY
   Person