Automate assignment queue with sql - sql

Question

I have a table that get updated every weeknight.
Someone then pull the table down, assigns values where the QueueT is null based on the number already assigned out and the type.
Think of it as a queueing system to even out workflow as evenly as possible.
Im stuck on attempting to automate the assignment piece
http://sqlfiddle.com/#!3/6a657/1
shows how much is assigned to each person, but how would i got about updating the table to assign each person based on type and even the assignments out as much as possible?
-- create temp table code if needed
create table #tempqueue
(
QueueT varchar(20)
,Type varchar(20)
)
insert into #tempqueue
(
QueueT
,Type
)
values
( 'bob' , 'type1'),
( 'bob' , 'type1'),
( 'john' , 'type2'),
( 'john' , 'type2'),
( 'john' , 'type2'),
( 'null' , 'type1'),
( 'null' , 'type1'),
( 'null' , 'type1'),
( 'null' , 'type1'),
( 'null' , 'type2'),
( 'null' , 'type2'),
( 'tim' , 'type1'),
( 'bob' , 'type1'),
( 'jill' , 'type2'),
( 'jack' , 'type2'),
( 'john' , 'type2'),
( 'null' , 'type1'),
( 'null' , 'type1'),
( 'null' , 'type1'),
( 'null' , 'type1'),
( 'null' , 'type2'),
( 'null' , 'type2'),
( 'null' , 'type2')
select
QueueT
,type
,count(Type) counttype
from #tempqueue
group by
QueueT
,type

Answer 1

First, you need a unique id for the table so each record can be updated individually:
create table tempqueue
(
id int identity(1,1)
,QueueT varchar(20)
,Type varchar(20)
)
Then you can update it using a couple sub queries, min, count, and the row_number windowed function:
create table tempqueue
(
id int identity(1,1)
,QueueT varchar(20)
,Type varchar(20)
)
insert into tempqueue
(
QueueT
,Type
)
values
( 'bob' , 'type1'),
( 'bob' , 'type1'),
( 'john' , 'type2'),
( 'john' , 'type2'),
( 'john' , 'type2'),
( null , 'type1'),
( null , 'type1'),
( null , 'type3'),
( null , 'type1'),
( null , 'type2'),
( null , 'type2'),
( 'tim' , 'type1'),
( 'bob' , 'type1'),
( 'jill' , 'type2'),
( 'jack' , 'type2'),
( 'john' , 'type2'),
( null , 'type1'),
( null , 'type1'),
( null , 'type1'),
( null , 'type1'),
( null , 'type2'),
( null , 'type2'),
( null , 'type2')
-- loop through records until no records are updated
declare #rows_updated int = 1
while #rows_updated > 0
begin
update t
set t.QueueT = u.QueueT
from tempqueue t
-- get min record id per type where QueueT is null
inner join (select Type,min(id) id
from tempqueue
where QueueT is null
group by Type) id
on id.Type = t.Type
and id.id = t.id
-- get QueueT for each Type with the least count
inner join (select QueueT,Type,
row_number() over(partition by Type order by cnt) lst
from (select QueueT,Type,count(*) cnt
from tempqueue
where QueueT is not null
group by QueueT,Type)c)u
on u.Type = id.Type
and u.lst = 1
set #rows_updated = ##rowcount
end
select QueueT,Type,count(*) cnt
from tempqueue
group by QueueT,Type
SQL FIDDLE