SQL Query for sorting and getting unique count - mysql

Question

I have a table which consists of the following details
Customer
Deal
DealStage
A
D1
Lost
A
D2
Won
A
D3
Contacted
B
D4
Conatcted
B
D5
Lost
C
D6
Lost
D
D7
Lost
I have to develop a query where I should get the unique highest stage for each customer. The Stage priority is Won > Contacted > Lost. For Example, A is having three deals which are Won, Lost, and Contacted. So I should be considering Won. Similarly Contacted for B and Lost for C and D
Is it possible to get an Output like
Customer
Highets Stage
A
Won
B
Contacted
C
Lost
D
Lost
By this, I can generate a pivot table that looks like
Stage
CustomerCount
Won
1
Contacted
1
Lost
2
Thanks in Advance

Answer 1

One option uses aggregation and field():
select customer,
case min(field(deal_stage, 'Won', 'Contacted', 'Lost'))
when 1 then 'Won'
when 2 then 'Contacted'
when 3 then 'Lost'
end as highest_stage
from mytable
group by customer
Actually we could combine this with elt():
select customer,
elt(
min(field(deal_stage, 'Won', 'Contacted', 'Lost')),
'Won', 'Contacted', 'Lost'
) as highest_stage
from mytable
group by customer
You can then generate the final result with another level of aggregation:
select highest_stage, count(*)
from (
select customer,
elt(
min(field(deal_stage, 'Won', 'Contacted', 'Lost')),
'Won', 'Contacted', 'Lost'
) as highest_stage
from mytable
group by customer
) t
group by highest_stage

Answer 2

Use windows function as follows:
select * from
(select t.*,
row_number() over (partition by customer
order by case when dealstage = 'Won' then 1
when dealstage = 'Contacted' then 2
when dealstage = 'Lost' then 3
end
) as rn
from your_table t)
where rn = 1;

Answer 3

These are really two different problems. I would, in fact, recommend different approaches to the two. For the first, conditional aggregation:
select customer,
coalesce(max(case when state = 'Won' then state end),
max(case when state = 'Contacted' then state end),
max(case when state = 'Lost' then state end)
) as biggest_state
from t
group by customer;
However, for your final result, I would recommend a correlated subquery:
select t.state, count(*)
from t
where t.state = (select t2.state
from t2
where t2.customer = t.customer
order by field(state, 'Won', 'Contact', 'Lost')
limit 1
)
group by t.state;
Note: This assumes that the original data does not have duplicate rows. If it does, then count(distinct) is one adjustment.