Question

I’ve got a table:

select personID, categoryCode from entries;

6300936427  083
6314642671  084
6314742066  081
6346724201  083
...

I can count the number of persons in each group by:

select categoryCode, count(e.ID)
from entries e
group by e.categoryCode
order by e.categoryCode;

060 56
062 15
081 377
082 374

I want to do the same calculation, but for some choosen categories I want to count them together. For instance I want if categoryCode IN (‘081’, ‘082’) I wish to count results for them. And my result set should be calculated as:

select ...

060 56
062 15
080 751 --(377 + 374) counts, that correspond to 081 and 082 categoryGroup

How can I archive this using Oracle analytical functions? (Oracle version 10)

Answer 1

Steven’s query can be rewritten:

SELECT 
       CASE  
           WHEN t.categoryCode in ('083', '084') THEN '080' 
           ELSE t.categoryCode 
       END AS combinedCategoryCode, 
       count(e.id) AS combinedCount 
FROM 
   entries t 
GROUP BY  
       CASE  
           WHEN t.categoryCode in ('083', '084') THEN '080' 
           ELSE t.categoryCode 
       END 
ORDER BY 1; 

But: You can create a configuration table, config_categ

categoryCode  categ_result
060           060 
062           062
081           080
082           080

and the query will be:

SELECT 
   c.categ_result, 
   count(e.id) AS combinedCount 
FROM 
   entries t 
   join config_categ c on (t.categoryCode = c.categoryCode) 
GROUP BY  
   c.categ_result    
ORDER BY 1; 

PS: You don’t need a analytic function for this. It is a simple group by.