How do I modify my SQL Statement so each Project has (x) Judges and each Judge participates evenly among their population?

Question

How do I modify my SQL Statement so each Project has 4 unique judges and each Judge evenly judges the same number of projects for their assigned division and category?

Requirements

Population Project needs to be reviewed by Population Judge (x) times. x = 4

• Each Project is grouped by Division and Category.

• Each Judge is grouped by Division and Category.

• Each Project must be reviewed by (x) unique Judges.

• Each Judge should never review the same project twice.
• Each Judge should be assigned an equal number of projects to review as the other judges in their division and category grouping.

Sample Source Judge Table

create table judges(judge_id, division, category) as (
    select 68, 'Elementary', 'ANY' from dual union all
    select 19, 'Elementary', 'ANY' from dual union all
    select 22, 'Elementary', 'ANY' from dual union all
    select 32, 'Elementary', 'ANY' from dual union all
    select 33, 'Elementary', 'ANY' from dual union all
    select 37, 'Elementary', 'ANY' from dual union all
    select 38, 'Elementary', 'ANY' from dual union all
    select 40, 'Elementary', 'ANY' from dual union all
    select 47, 'Elementary', 'ANY' from dual union all
    select 62, 'Elementary', 'ANY' from dual union all
    select 63, 'Elementary', 'ANY' from dual union all
    select 13, 'Elementary', 'ANY' from dual union all
    select 36, 'Elementary', 'ANY' from dual union all
    select 55, 'Elementary', 'ANY' from dual union all
    select 59, 'Elementary', 'ANY' from dual union all
    select 60, 'Elementary', 'ANY' from dual union all
    select 9, 'Junior', 'EC' from dual union all
    select 10, 'Junior', 'EC' from dual union all
    select 48, 'Junior', 'EC' from dual union all
    select 11, 'Junior', 'LS' from dual union all
    select 21, 'Junior', 'LS' from dual union all
    select 23, 'Junior', 'LS' from dual union all
    select 26, 'Junior', 'LS' from dual union all
    select 31, 'Junior', 'LS' from dual union all
    select 80, 'Junior', 'LS' from dual union all
    select 14, 'Junior', 'PE' from dual union all
    select 15, 'Junior', 'PE' from dual union all
    select 24, 'Junior', 'PE' from dual union all
    select 29, 'Junior', 'PE' from dual union all
    select 30, 'Junior', 'PE' from dual union all
    select 43, 'Junior', 'PE' from dual union all
    select 53, 'Junior', 'PE' from dual union all
    select 56, 'Junior', 'PE' from dual union all
    select 57, 'Junior', 'PE' from dual union all
    select 58, 'Junior', 'PE' from dual union all
    select 65, 'Junior', 'PE' from dual union all
    select 67, 'Junior', 'PE' from dual union all
    select 69, 'Junior', 'PE' from dual union all
    select 8, 'Senior', 'ANY' from dual union all
    select 18, 'Senior', 'ANY' from dual union all
    select 20, 'Senior', 'ANY' from dual union all
    select 35, 'Senior', 'ANY' from dual union all
    select 66, 'Senior', 'ANY' from dual union all
    select 39, 'Senior', 'ANY' from dual union all
    select 70, 'Senior', 'ANY' from dual union all
    select 71, 'Senior', 'ANY' from dual union all
    select 74, 'Senior', 'ANY' from dual union all
    select 6, 'Senior', 'ANY' from dual union all
    select 44, 'Senior', 'ANY' from dual union all
    select 45, 'Senior', 'ANY' from dual union all
    select 49, 'Senior', 'ANY' from dual union all
    select 61, 'Senior', 'ANY' from dual union all
    select 64, 'Senior', 'ANY' from dual union all
    select 72, 'Senior', 'ANY' from dual union all
    select 75, 'Senior', 'ANY' from dual union all
    select 79, 'Senior', 'ANY' from dual union all
    select 82, 'Senior', 'ANY' from dual
);

Sample Source Project Table

create table projects(project_id, division, category) as (
     select 39, 'Elementary', 'ANY' from dual union all
    select 40, 'Elementary', 'ANY' from dual union all
    select 47, 'Elementary', 'ANY' from dual union all
    select 48, 'Elementary', 'ANY' from dual union all
    select 56, 'Elementary', 'ANY' from dual union all
    select 57, 'Elementary', 'ANY' from dual union all
    select 58, 'Elementary', 'ANY' from dual union all
    select 60, 'Elementary', 'ANY' from dual union all
    select 65, 'Elementary', 'ANY' from dual union all
    select 66, 'Elementary', 'ANY' from dual union all
    select 93, 'Elementary', 'ANY' from dual union all
    select 94, 'Elementary', 'ANY' from dual union all
    select 97, 'Elementary', 'ANY' from dual union all
    select 104, 'Elementary', 'ANY' from dual union all
    select 105, 'Elementary', 'ANY' from dual union all
    select 107, 'Elementary', 'ANY' from dual union all
    select 110, 'Elementary', 'ANY' from dual union all
    select 112, 'Elementary', 'ANY' from dual union all
    select 114, 'Elementary', 'ANY' from dual union all
    select 117, 'Elementary', 'ANY' from dual union all
    select 120, 'Elementary', 'ANY' from dual union all
    select 121, 'Elementary', 'ANY' from dual union all
    select 123, 'Elementary', 'ANY' from dual union all
    select 124, 'Elementary', 'ANY' from dual union all
    select 126, 'Elementary', 'ANY' from dual union all
    select 127, 'Elementary', 'ANY' from dual union all
    select 128, 'Elementary', 'ANY' from dual union all
    select 133, 'Elementary', 'ANY' from dual union all
    select 134, 'Elementary', 'ANY' from dual union all
    select 136, 'Elementary', 'ANY' from dual union all
    select 140, 'Elementary', 'ANY' from dual union all
    select 142, 'Elementary', 'ANY' from dual union all
    select 152, 'Elementary', 'ANY' from dual union all
    select 153, 'Elementary', 'ANY' from dual union all
    select 162, 'Elementary', 'ANY' from dual union all
    select 167, 'Elementary', 'ANY' from dual union all
    select 173, 'Elementary', 'ANY' from dual union all
    select 174, 'Elementary', 'ANY' from dual union all
    select 188, 'Elementary', 'ANY' from dual union all
    select 27, 'Junior', 'EC' from dual union all
    select 67, 'Junior', 'EC' from dual union all
    select 82, 'Junior', 'EC' from dual union all
    select 83, 'Junior', 'EC' from dual union all
    select 99, 'Junior', 'EC' from dual union all
    select 113, 'Junior', 'EC' from dual union all
    select 115, 'Junior', 'EC' from dual union all
    select 149, 'Junior', 'EC' from dual union all
    select 164, 'Junior', 'EC' from dual union all
    select 169, 'Junior', 'EC' from dual union all
    select 185, 'Junior', 'EC' from dual union all
    select 189, 'Junior', 'EC' from dual union all
    select 18, 'Junior', 'LS' from dual union all
    select 19, 'Junior', 'LS' from dual union all
    select 20, 'Junior', 'LS' from dual union all
    select 21, 'Junior', 'LS' from dual union all
    select 23, 'Junior', 'LS' from dual union all
    select 24, 'Junior', 'LS' from dual union all
    select 26, 'Junior', 'LS' from dual union all
    select 28, 'Junior', 'LS' from dual union all
    select 29, 'Junior', 'LS' from dual union all
    select 30, 'Junior', 'LS' from dual union all
    select 78, 'Junior', 'LS' from dual union all
    select 80, 'Junior', 'LS' from dual union all
    select 90, 'Junior', 'LS' from dual union all
    select 91, 'Junior', 'LS' from dual union all
    select 106, 'Junior', 'LS' from dual union all
    select 144, 'Junior', 'LS' from dual union all
    select 150, 'Junior', 'LS' from dual union all
    select 151, 'Junior', 'LS' from dual union all
    select 156, 'Junior', 'LS' from dual union all
    select 157, 'Junior', 'LS' from dual union all
    select 159, 'Junior', 'LS' from dual union all
    select 161, 'Junior', 'LS' from dual union all
    select 165, 'Junior', 'LS' from dual union all
    select 166, 'Junior', 'LS' from dual union all
    select 168, 'Junior', 'LS' from dual union all
    select 178, 'Junior', 'LS' from dual union all
    select 180, 'Junior', 'LS' from dual union all
    select 187, 'Junior', 'LS' from dual union all
    select 22, 'Junior', 'PE' from dual union all
    select 59, 'Junior', 'PE' from dual union all
    select 61, 'Junior', 'PE' from dual union all
    select 74, 'Junior', 'PE' from dual union all
    select 81, 'Junior', 'PE' from dual union all
    select 95, 'Junior', 'PE' from dual union all
    select 96, 'Junior', 'PE' from dual union all
    select 116, 'Junior', 'PE' from dual union all
    select 145, 'Junior', 'PE' from dual union all
    select 148, 'Junior', 'PE' from dual union all
    select 158, 'Junior', 'PE' from dual union all
    select 160, 'Junior', 'PE' from dual union all
    select 172, 'Junior', 'PE' from dual union all
    select 176, 'Junior', 'PE' from dual union all
    select 181, 'Junior', 'PE' from dual union all
    select 186, 'Junior', 'PE' from dual union all
    select 14, 'Senior', 'ANY' from dual union all
    select 15, 'Senior', 'ANY' from dual union all
    select 42, 'Senior', 'ANY' from dual union all
    select 43, 'Senior', 'ANY' from dual union all
    select 44, 'Senior', 'ANY' from dual union all
    select 45, 'Senior', 'ANY' from dual union all
    select 46, 'Senior', 'ANY' from dual union all
    select 49, 'Senior', 'ANY' from dual union all
    select 51, 'Senior', 'ANY' from dual union all
    select 52, 'Senior', 'ANY' from dual union all
    select 53, 'Senior', 'ANY' from dual union all
    select 54, 'Senior', 'ANY' from dual union all
    select 75, 'Senior', 'ANY' from dual union all
    select 76, 'Senior', 'ANY' from dual union all
    select 77, 'Senior', 'ANY' from dual union all
    select 92, 'Senior', 'ANY' from dual union all
    select 108, 'Senior', 'ANY' from dual union all
    select 118, 'Senior', 'ANY' from dual union all
    select 119, 'Senior', 'ANY' from dual union all
    select 125, 'Senior', 'ANY' from dual union all
    select 131, 'Senior', 'ANY' from dual union all
    select 132, 'Senior', 'ANY' from dual union all
    select 135, 'Senior', 'ANY' from dual union all
    select 137, 'Senior', 'ANY' from dual union all
    select 138, 'Senior', 'ANY' from dual union all
    select 139, 'Senior', 'ANY' from dual union all
    select 141, 'Senior', 'ANY' from dual union all
    select 143, 'Senior', 'ANY' from dual union all
    select 146, 'Senior', 'ANY' from dual union all
    select 154, 'Senior', 'ANY' from dual union all
    select 171, 'Senior', 'ANY' from dual
);

Oracle SQL Code

select 
     project_id
    ,division
    ,category
    ,judge_id
    ,best_match
from(
    select 
         project.project_id
        ,project.division
        ,project.category
        ,judge.judge_id
        ,row_number() over(
            partition by project.project_id 
            order by dbms_random.value
        ) as best_match
    from frsf_fair.project_division_category project
    left join (
        select 
            judge_id
            ,division
            ,category
            ,row_number() over(
                partition by division 
                order by dbms_random.value
            ) as r
        from frsf_fair.judge_division_category
        ) judge on project.division = judge.division 
            and project.category = judge.category   
) assignment
where best_match <= 4

Data Output Example

PROJECT_ID  DIVISION    CATEGORY    JUDGE_ID    BEST_MATCH
14  Senior  ANY 72  1
14  Senior  ANY 74  2
14  Senior  ANY 20  3
14  Senior  ANY 44  4

15  Senior  ANY 79  1
15  Senior  ANY 39  2
15  Senior  ANY 75  3
15  Senior  ANY 20  4

18  Junior  LS  23  1
18  Junior  LS  31  2
18  Junior  LS  26  3
18  Junior  LS  21  4

Problem

The number of count(*)/projects should be distributed evenly among the Division and Category for a pool a judge. Instead, some judges are assigned to 20 projects while others are assigned to very few. I don’t know how to modify my query so each judge must be reference an equal number of times amongst the Project Division and Category grouping. I want to ensure equal participation.

JUDGE_ID    COUNT(*)
64  8
72  16
23  20
57  4
14  4
6   4
58  9

Answer

I came up with a solution utilizing procedures in my Oracle database.

My approach was to loop through each project id. While inside my loop it would loop 1 to the number of assignments I required, in this case, 4.

1. We needed to pull out a random judge id from a list of judges by a count of how many assignments they have already been given in ascending order. I wanted to use the lowest number of assignments first.

2. Their assignment count if bumped +1

3. We update the values in the final list table

4. We loop until the number of assignments by project is given and then the next project is assessed.

   create or replace procedure random_judge_project_list as

   assign_count    number := 0;
   next_count      number := 1;
   
   assignments     number := 4;
   jid             number;
   sql_stmt         varchar2(4000);
   
   location varchar2(20);
   

   begin

   execute immediate 'truncate table judge_project_list';
   execute immediate 'update judge_assignment_count set assignment_count = 0';
   
   /*We First Need to Loop through Each Project*/
   for project in (
       select 
           project_id
           ,division
           ,category as source_category
           ,case division 
               when 'Junior' then category
               else 'ANY'
           end as category      
       from projects a
       order by division asc, category asc
   )
   loop
       /*While Looping we then need to assign judges randomly*/   
       for assign in 1 .. assignments
       loop
   
               select judge_id
               into jid
               from(
                   select *
                   from judge_assignment_count
                   where division = project.division
                       and judge_id not in (select judge_id from judge_project_list where project_id = project.project_id)
                   order by assignment_count asc, dbms_random.random asc
               ) where rownum = 1
           ;
   
           select assignment_count
           into assign_count
           from judge_assignment_count
           where judge_id = jid 
           and rownum = 1
           ;
   
           next_count := assign_count + 1;
   
           --dbms_output.put_line(sql_stmt);
   
           --execute immediate sql_stmt into jid;
   
           insert into judge_project_list (project_id, judge_id, division, category) values (project.project_id, jid, project.division, project.category);
   
           execute immediate 'update judge_assignment_count set assignment_count = ' || next_count || ' where judge_id = ' || jid;
   
   
   
       end loop;
   
   end loop;
   
   commit;
   

   end;