hoe kan ik de status tellen die is gewijzigd/bijgewerkt door categorieën voor een specifieke maand?

SQL DEMO

SELECT q.year
     , q.month
     , q.name
     , COUNT(CASE WHEN q.last_status = 2 THEN 1 END) as pre_implementation
     , COUNT(CASE WHEN q.last_status = 3 
                   AND q.previous_status = 2 THEN 1 END) as implementation_operation
     , COUNT(CASE WHEN q.last_status = 3 
                   AND (q.previous_status = 1 or q.previous_status IS NULL)
                  THEN 1 END) as pre_operation
FROM (
    SELECT *, (SELECT MAX(p.status_id)
               FROM project_status p
               WHERE p.time < CONCAT(t.year,'/', t.month,'/1')
                 AND p.project_id = t.project_id
               ) as previous_status
    FROM (
        SELECT YEAR(time) as year
             , MONTH(time) as month
             , c.name
             , ps.project_id
             , MAX(status_id) as last_status
        FROM project_status ps
        JOIN projects p
          ON ps.project_id = p. project_id
        JOIN investments i 
          ON p.investment_id = i.investment_id
        JOIN categories c
          ON i.cat_id = c.cat_id
        GROUP BY YEAR(time), MONTH(time), c.name, ps.project_id
    ) t
) q
GROUP BY q.year, q.month, q.name

UITVOER

+--------+-------+---------------+--------------------+--------------------------+---------------+
|  year  | month |     name      | pre_implementation | implementation_operation | pre_operation |
+--------+-------+---------------+--------------------+--------------------------+---------------+
| 2019   |     2 | Technology    |                  0 |                        0 |             0 |
| 2019   |     3 | Technology    |                  1 |                        0 |             0 |
| 2019   |     4 | services      |                  0 |                        0 |             0 |
| 2019   |     5 | agriculture   |                  0 |                        0 |             0 |
+--------+-------+---------------+--------------------+--------------------------+---------------+
| 2019   |     8 | Technology    |                  0 |                        1 |             0 |
| 2019   |     8 | agriculture   |                  1 |                        0 |             1 |
| 2019   |     8 | services      |                  0 |                        0 |             1 |
| 2019   |     8 | manufactures  |                  1 |                        0 |             0 |
+--------+-------+---------------+--------------------+--------------------------+---------------+