Distinct Count Query - mysql

Question

I have a table below:
Item Status1 Status2
-----------------------------
A Good NULL
A Good NULL
A Good NULL
A Bad Good
B Bad Good
B Good NULL
C Good NULL
C Good NULL
C Good NULL
D Bad Good
Now, I'm thinking off writing a query which gives me the result below:
Item Good Bad
-----------------------------
A 4 1
B 2 1
C 3 0
D 1 1
Distinct in the Item column and the count of Good and Bad for each Item where NULL is not counted.
The column name can be of anything (I just kept it as Good and Bad in my second table).
Any suggestions/ideas on how to achieve my desired results?

Answer 1

Use UNION ALL & do aggregation :
select item, sum(status = 'good'), sum(status = 'bad')
from (select item, status1 as status
from table t
union all
select item, status2
from table t
) t
group by item;

Answer 2

You can use union all and conditional aggregation
select item, count(case when status1='good' then 1 end) as good,
count(case when status1='bad' then 1 end) as bad
from
(
select item , status1 from tablename
union all
select item , status2 from tablename
)A group by item

Answer 3

use union and case when
select Item, sum(case when status = 'good' then 1 else 0 end) as good,
sum ( case when status = 'bad' then 1 else 0 end) as bad
from (select Item, Status1 as status
from table_name
union all
select Item, Status2
from table_name
) t
group by Item;

Answer 4

There's no need for UNION, simply apply some logic.
select Item
,sum(case when Status1 = 'Good' then 1 else 0 end +
case when Status2 = 'Good' then 1 else 0 end) as good
,sum(case when Status1 = 'Bad' then 1 else 0 end +
case when Status2 = 'Bad' then 1 else 0 end) as bad
from tab
group by Item
or
select Item
,count(case when Status1 = 'Good' then 1 end) +
count(case when Status2 = 'Good' then 1 end) as good
,count(case when Status1 = 'Bad' then 1 end) +
count(case when Status2 = 'Bad' then 1 end) as good
from tab
group by Item

Answer 5

You can use sub-query and then apply sum function in outer query
select distinct(item) as item, sum(S1G+S2G) as Good,sum(S1B+S2B) as Bad from ( select item, CASE WHEN status1 ='Good' THEN 1 ELSE 0 END as S1G, CASE WHEN status2 ='Good' THEN 1 ELSE 0 END as S2G, CASE WHEN status2 ='Bad' THEN 1 ELSE 0 END as S2B, CASE WHEN status1 ='Bad' THEN 1 ELSE 0 END as S1B from t1 ) as b group by item
Here is demo