Your ABAP SQL SELECT statement contains the following FIELDS list: field1, field2, sum(field4). Only one of the following GROUP BY clauses causes a syntax error. Which one?

The correct choice is associated with an understanding of how the SQL GROUP BY clause operates alongside aggregate functions like SUM. In this scenario, the SELECT statement specifies fields and an aggregate function, namely SUM(field4). When using aggregate functions in a query, any columns selected must either be part of an aggregate function (like SUM) or be included in the GROUP BY clause.

In this case, the FIELDS list includes field1, field2, and an aggregated value SUM(field4). Therefore, to write a valid GROUP BY clause, you need to include all non-aggregated fields in the GROUP BY clause.

Both field1 and field2 are non-aggregated fields in the SELECT statement. Thus, having a GROUP BY clause that only includes field1 does not satisfy the requirement of including all relevant non-aggregated columns, which leads to a syntax error. The other options correctly group by the necessary fields or provide combinations that do not violate the SQL syntax rules for aggregation.

In summary, the GROUP BY clause should consistently match the fields specified in the SELECT statement to avoid syntax issues, and that is why the choice involving only grouping by field1 leads to a syntax error