Home/ Questions/Q 7612007
In Process

The Archive Base Latest Questions

Editorial Team
  • 0
Asked: 2026-05-31T01:48:20+00:00

I come across this pattern occasionally and I haven’t found a terribly satisfactory way

  • 0

I come across this pattern occasionally and I haven’t found a terribly satisfactory way to solve it.

Say I have a employee table and an review table. Each employee can have more than one review. I want to find all the employees who have at least one “good” review but no “bad” reviews.

I haven’t figured out how to make subselects work without knowing the employee ID before hand and I haven’t figured out the right combination of joins to make this happen.

Is there a way to do this WITHOUT stored procedures, functions or bringing the data server side? I’ve gotten it to work with those but I’m sure there’s another way.

Share

Leave an answer

You must login to add an answer.

Need An Account,

1 Answer

  1. Editorial Team

    Since you haven’t posted your DB Structure, I made some assumptions and simplifications (regarding the rating column, which probably is number and not a character field). Adjust accordingly.

    Solution 1: Using Joins

    select distinct e.EmployeeId, e.Name
from employee e
left join reviews r1 on e.EmployeeId = r1.EmployeeId and r1.rating = 'good'
left join reviews r2 on e.EmployeeId = r2.EmployeeId and r1.rating = 'bad'
where r1.ReviewId is not null --meaning there's at least one
and r2.ReviewId is null --meaning there's no bad review

    Solution 2: Grouping By and Filtering with Conditional Count

    select e.EmployeeId, max(e.Name) Name
from employee e
left join reviews r on e.EmployeeId = r.EmployeeId
group by e.EmployeeId
having count(case r.rating when 'good' then 1 else null end) > 0
and  count(case r.rating when 'bad' then 1 else null end) = 0

    Both solutions are SQL ANSI compatible, which means both work with any RDBMS flavor that fully support SQL ANSI standards (which is true for most RDBMS).

    As pointed out by @onedaywhen, the code will not work in MS Access (have not tested, I’m trusting in his expertise on the subject).

    But I have one saying on this (which might make some people upset): I hardly consider MS Access a RDBMS. I have worked with it in the past. Once you move on (Oracle, SQL Server, Firebird, PostGreSQL, MySQL, you name it), you do not ever want to come back. Seriously.

    • 0