Обсуждение: [GENERAL] count records in two different table joined by

Поиск
Список
Период
Сортировка

[GENERAL] count records in two different table joined by

От
Patrick B
Дата:
Hi guys!

I've got 2 tables, and I need to get some data between them.

test1:
WITH account_status AS (
select 
CASE 
  WHEN regdate = 1 THEN 'yes'
  WHEN regdate = 2 THEN 'no'
  from test1
  end as status_a
)

select status_a from account_status group by status_a

test2:
WITH user_status AS (
select 
CASE 
  WHEN regdate = 1 THEN 'yes'
  WHEN regdate = 2 THEN 'no'
  from test1
  join test2 as t2 on t2.test1_id = t1.id
  end as status_a
)

select status_a from user_status group by status_a

It works fine.. but I would like to get that data in one single query.. How can I do that?

I'm using Postgres 9.3.

Thanks!
Patrick

Re: [GENERAL] count records in two different table joined by

От
Thomas Markus
Дата:
Hi,

Am 07.07.17 um 12:16 schrieb Patrick B:
Hi guys!

I've got 2 tables, and I need to get some data between them.

test1:
WITH account_status AS (
select 
CASE 
  WHEN regdate = 1 THEN 'yes'
  WHEN regdate = 2 THEN 'no'
  from test1
  end as status_a
)

select status_a from account_status group by status_a

test2:
WITH user_status AS (
select 
CASE 
  WHEN regdate = 1 THEN 'yes'
  WHEN regdate = 2 THEN 'no'
  from test1
  join test2 as t2 on t2.test1_id = t1.id
  end as status_a
)

select status_a from user_status group by status_a

It works fine.. but I would like to get that data in one single query.. How can I do that?

I'm using Postgres 9.3.

Thanks!
Patrick

one possibility is:

select distinct
    case
        when regdate = 1 THEN 'yes'
        when regdate = 2 THEN 'no'
    end as status_a
    , t2.id is null as test2exists
from test1 t1 left join test2 t2 on t2.test1_id = t1.id

hth
Thomas

Re: [GENERAL] count records in two different table joined by

От
Patrick B
Дата:


2017-07-07 22:32 GMT+12:00 Thomas Markus <t.markus@proventis.net>:
Hi,

Am 07.07.17 um 12:16 schrieb Patrick B:
Hi guys!

I've got 2 tables, and I need to get some data between them.

test1:
WITH account_status AS (
select 
CASE 
  WHEN regdate = 1 THEN 'yes'
  WHEN regdate = 2 THEN 'no'
  from test1
  end as status_a
)

select status_a from account_status group by status_a

test2:
WITH user_status AS (
select 
CASE 
  WHEN regdate = 1 THEN 'yes'
  WHEN regdate = 2 THEN 'no'
  from test1
  join test2 as t2 on t2.test1_id = t1.id
  end as status_a
)

select status_a from user_status group by status_a

It works fine.. but I would like to get that data in one single query.. How can I do that?

I'm using Postgres 9.3.

Thanks!
Patrick

one possibility is:

select distinct
    case
        when regdate = 1 THEN 'yes'
        when regdate = 2 THEN 'no'
    end as status_a
    , t2.id is null as test2exists
from test1 t1 left join test2 t2 on t2.test1_id = t1.id

hth
Thomas



hmmm... not really

I want this to work:

WITH account_status AS (
select 
CASE 
  WHEN regdate = 1 THEN 'yes'
  WHEN regdate = 2 THEN 'no'
end as status_a,
count(t2.id) as t2_count
  from test1 as t1
join test2 as t2 on t2.test1_id = t1.id
  end as status_a
)

select 
status_a, 
t2_count,
count(*)
from account_status group by status_a, t2_count

Re: [GENERAL] count records in two different table joined by

От
"David G. Johnston"
Дата:
On Fri, Jul 7, 2017 at 3:49 AM, Patrick B <patrickbakerbr@gmail.com> wrote:
I want this to work:

WITH account_status AS (
select 
CASE 
  WHEN regdate = 1 THEN 'yes'
  WHEN regdate = 2 THEN 'no'
end as status_a,
count(t2.id) as t2_count
  from test1 as t1
join test2 as t2 on t2.test1_id = t1.id
  end as status_a
)

select 
status_a, 
t2_count,
count(*)
from account_status group by status_a, t2_count

​Usually aggregates and joins introduce the possibility of double-counting.  Generally the simplest way is to write three queries.

WITH agg1 AS (),
agg2 AS ()
SELECT (SELECT agg1.result) AS ...,
(SELECT agg2.result) ...;

Depending on the data you can sometimes be a bit more efficient by doing:

SELECT agg(DISTSINCT col) AS ...

If since the distinct portion would remove the inherent duplication being introduced by the join.

David J.