combine 2 sql select count statements

Question

I ahave 2 simple count queries:

select count (*) from t_object
select count (*) from t_diagram

How is the simplest way to combine their result (sum)?

jarlh · Accepted Answer · 2015-06-03T09:07:58.063

3

Use UNION ALL to get two different count:

select count (*), 't_object count' from t_object
union all
select count (*), 't_diagram count' from t_diagram

To get the sum of the counts, use a derived table:

select sum(dt.cnt) from
(
 select count(*) as cnt from t_object
 union all
 select count(*) as cnt from t_diagram
) dt

Or, use a sub-query:

select count(*) + (select count(*) from t_diagram) from t_object

edited Jun 03 '15 at 09:07

answered Jun 03 '15 at 09:06

jarlh

This would return an unordered rowset with two rows containing two numbers. You wouldn't be able to tell which was which. – Andomar Jun 03 '15 at 09:07
@jarlh, Thanks. I would like to get sum. – user3165438 Jun 03 '15 at 09:07
2

Now edited, result now includes info on which count. – jarlh Jun 03 '15 at 09:08

Andomar · Answer 2 · 2015-06-03T09:22:20.353

2

Depends on what you mean by "combine". To sum them up:

select  (select count (*) from t_object) + count(*) as combined_count
from    t_diagram

edited Jun 03 '15 at 09:22

answered Jun 03 '15 at 09:05

Andomar

1

Thanks. I get the following error: `The select statement includes a ersversed word or an argument name that misspelled or missing, or the punctuation is incorrect.` Any ideas? – user3165438 Jun 03 '15 at 09:11
Looks like you need at least one source table. Jarlh's answer already had that btw. – Andomar Jun 03 '15 at 09:22

2 Answers2