Accessing a temporary table multiple times in MySql

Question

I have tried to use a temporary table as an intermediate result holder for a SELECT statement. The problem is though that I can\'t access the temp table multiple times in ot

Answer 1

For this problem, where the temporary table is only to be read, I create a second temporary table as a copy of the first then use this in the query:

CREATE TEMPORARY TABLE t2 as (SELECT * FROM dates_with_entries);

Then

SELECT 
...
FROM (SELECT entrie_date AS datum FROM dates_with_entries ) AS sub_result
INNER JOIN project_times
    ON sub_result.datum = project_times.datum AND project_times.user_id = 20
LEFT JOIN works AS w ON project_times.work_id = w.id
LEFT JOIN sub_projects AS sp ON sp.id = w.sub_project_id
LEFT JOIN projects AS p ON p.id = sp.project_id
GROUP BY datum
UNION(
    SELECT
      ..
  FROM (SELECT entrie_date AS datum FROM t2) AS sub_result
  INNER JOIN project_times AS pt ON pt.datum = sub_result.datum
  INNER JOIN works AS w on w.id = pt.work_id
  INNER JOIN sub_projects AS sp on w.sub_project_id = sp.id
  INNER JOIN projects AS p ON sp.project_id = p.id
  WHERE pt.user_id = 20
);