When using a GROUP BY clause every field in the SELECT list must be either:
- One of the GROUP BY terms - in this case region
- An aggregate function - for example SUM or COUNT
- An expression based on the above
In the example the field
name may not be used
on the SELECT line.
In a group by line each region shows up only once - however in
a typical region such as Africa there are several different
name values. WHich one should SQL pick?
- Remove the offending field from the SELECT line
- Add the field to the GROUP BY clause
- Aggregate the offending field