Question

I have following problem:
I want to count data in one table, count data in second table and compare countings in having clause, and display only that rows which have the same countings
Something like that:

SELECT bla
FROM T1 t1 JOIN T2 t2
ON t1.id = t2.id
HAVING COUNT(counted data from table1) = COUNT(counted data from table2)

Do you have any idea?
Cheers

Answer 1

Standard SQL:

SELECT t1.bla, t1.id, t1.counter, t2.counter
  FROM (SELECT t1.bla, t1.id, COUNT(counted_data_from_t1) AS counter
          FROM t1
         GROUP BY t1.bla, t1.id
       ) AS t1
  JOIN (SELECT t2.id, COUNT(counted_data_from_t2) AS counter
          FROM t2
         GROUP BY t2.id
       ) AS t2
    ON t1.id = t2.id AND t1.counter = t2.counter

Oracle SQL (because Oracle doesn’t like AS before table aliases):

SELECT t1.bla, t1.id, t1.counter, t2.counter
  FROM (SELECT t1.bla, t1.id, COUNT(counted_data_from_t1) AS counter
          FROM t1
         GROUP BY t1.bla, t1.id
       ) t1
  JOIN (SELECT t2.id, COUNT(counted_data_from_t2) AS counter
          FROM t2
         GROUP BY t2.id
       ) t2
    ON t1.id = t2.id AND t1.counter = t2.counter

You just have to decide where bla comes from; I nominated t1. I’m assuming that for any given value of t1.id, there is a single value of t1.bla. If there isn’t, then you need to explain much more clearly what you’re counting and where the various columns are, and what the keys of the tables are.

Update: Apologies for not noticing the Oracle tag and giving invalid Oracle syntax.