Question

I’m trying to write this query, that would calculate the average value of all the columns except the one that contains the type value, which I’m grouping the whole query by.

So for 4 types for example, each column in the resulting table will contain the average of all the other three type’s values, i need to exclude the current type’s rows.

As an example, if I was to calculate each type’s average value for itself, the query would look like:

SELECT

SUM(some value) / COUNT(TYPE)

FROM TEMPTABLE
GROUP BY TYPE

Now I’m trying to calculate the other three’s total average. Thanks.

Answer 1

You can do one query to get the distinct types, and LEFT JOIN the same table, checking for type-inequality:

SELECT t1.type,
       SUM(t2.some_value) / COUNT(t2.type)
FROM ( SELECT DISTINCT type FROM temptable ) t1
LEFT JOIN temptable t2 ON ( t1.type <> t2.type )
GROUP BY t1.type

Since you only want the average, you could replace the line

FROM ( SELECT DISTINCT type FROM temptable ) t1

by

FROM temptable t1

but the first solution might perform better, since the number of rows is reduced earlier.