如何在两个子查询中使用group by并对行数求和？

SELECT field1, COUNT(*) AS count1
FROM tableA
GROUP BY field1

SELECT field2, COUNT(*) AS count2
FROM tableB
GROUP BY field2

SELECT SUM(count1) AS total_count1, SUM(count2) AS total_count2
FROM (
  SELECT field1, COUNT(*) AS count1
  FROM tableA
  GROUP BY field1
) AS subquery1
JOIN (
  SELECT field2, COUNT(*) AS count2
  FROM tableB
  GROUP BY field2
) AS subquery2
ON subquery1.field1 = subquery2.field2