Re: avg() from multiple columns

Jason Tan wrote:
>
>
>If you want row by row averages try this:
>
>select (col1+col2+col3)/3 from table;
>
>If you wnat to average several columns over the whole table this seems to
>work:
>
>select avg(col1+col2+col3) from table;

Watch out for NULL values when doing this. x + x + NULL = NULL, not 2x

You might do better to do:

SELECT avg(col1) + avg(col2) + avg(col3)

or

SELECT avg(COALESCE(col1, 0) + COALESCE(col2, 0) + COALESCE(col3,0))

(the two are not equivalent).

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Oliver Elphick Oliver(dot)Elphick(at)lfix(dot)co(dot)uk
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