How can I count existing and non-existing values with MySQL?

Posted by jaya malladi on Stack Overflow See other posts from Stack Overflow or by jaya malladi
Published on 2012-11-15T06:11:00Z Indexed on 2012/11/15 11:01 UTC
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I am new to MySQL.

I have a table with answer ids. Answers can look like this:a1, a2, a3 ..., but due to some problems some are NULL, some are blank, and some are others like 1 a etc.

Now I want to calculate the count of ids with a1 a2 a3 distinctly. But how is it possible to do this leaving others like NULL, blanks and garbage.

The output should look like this

atype count 
a1      45
a2       0
a3      56

If there is no row entry for a particular answer, the count should be 0.

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