SQL Code Review - Something to Lookout for

When doing a code review one looks to see if the best practices are followed. Some are about the readability and therefore maintainability of the code, but, then there are some which could point to application logic traps. While reviewing a SQL I found something in production code, leading me to believe it could/should have been caught more easily with a code review itself, though there is no excuse that it was not found with the data validation/qa step.

The pattern is as following:- Select  grouping_attribute , max(descriptor_type_attribute), max(attribute_expiry_date)

From table Group by grouping_attribute The data has to do with licensing of certain professionals, and the descriptor_type_attribute is the identifier given by the licensing board and will have any expiry date associated with it. This query would have been fine if both the attributes followed the same sorting strategy, but it was not the case. So one could end up picking up a license number(descriptor_type_attribute) with wrong expiry date. Not the intended outcome. Part of the fault in my humble opinion lies with giving a _no postfix to the descriptor_type_attribute in the data model. A better query could be written using the analytical functions in Oracle, e.g.

Select grouping_attribute, descriptor_type_attribute, attribute_expiry_date from (

Select grouping_attribute, descriptor_type_attribute, attribute_expiry_date,

                Row_number() over(partition by grouping_attribute order by attribute_expiry_date desc) rn

From table

) q

Where q.rn=1