How to count distinct values that all satisfy a condition in MySQL?

Question

I'm trying to write a query to find distinct values in a particular field, count the number of occurrences of that value where for all instances of that particular value another column value is satisfied, and then display the results as follows (more explanation to follow):

Example db:

RowId    Status       MemberIdentifier
-----    ------       ----------------
1       In Progress   111111111
2       Complete      123456789
3       Not Started   146782452
4       Complete      111111111
5       Complete      123456789
6       Not Started   146782452
7       Complete      111111111

Desired Result:

Status         MemberIdentifierCount 
------         ---------------------- 
Not Started    1
In Progress    1
Complete       1

In the above query, the number of distinct MemberIdentifiers with a given Status are counted and displayed. If a MemberIdentifier has two rows with Status 'Complete' but one with Status 'In Progress,' it is grouped and counted as in progress (i.e., MemberIdentifier= 111111111). For a MemberIdentifier to be grouped and counted as complete, all of its rows must have a Status of 'Complete' (i.e., MemberIdentifier= 123456789). Any insight would be appreciated (MySQL newbie).

Answer 1

Per MemberIdentifier find the status you consider appropriate, e.g. 'In Progress' wins over 'Complete' and 'Not Started'. 'Not Started' wins over 'Complete'. Use conditional aggregation for this.

select status, count(*)
from
(
  select 
    case when sum(status = 'In Progress') > 0 then 'In Progress'
         when sum(status = 'Not Started') > 0 then 'Not Started'
         else 'Complete'
    end as status
  from mytable
  group by memberidentifier
) statuses
group by status;

Answer 2

SELECT max_status AS Status
     , COUNT(*) AS ct
    FROM (
        SELECT MAX(Status) AS max_status
            FROM tbl
            GROUP BY MemberIdentifier
         ) AS a
    GROUP BY max_status;

This takes advantage of how these strings compare: "In Progress" > "Complete". In doing so, it does random things to any other member with multiple Statuses.