Question

I am selecting a number of database columns from a MySQL database. I would like to count the number of returned MySQL rows from a particular set that is not NULL.

For example…

SELECT p.wavURL1, p.wavURL2, p.wavURL3, p.wavURL4,  etc.

Can I count in PHP the number of these that are not NULL?

Answer 1

If I understand your question correctly, this should do what you want:

SELECT COUNT(COALESCE(col1, col2, ..., col16)) AS cnt
FROM yourtable

See the MySQL manual for more details:

• COUNT – Returns a count of the number of non-NULL values of expr in the rows retrieved by a SELECT statement.
• COALESCE – Returns the first non-NULL value in the list, or NULL if there are no non-NULL values.