Snowflake : IN operator - snowflake-cloud-data-platform

Question

so I want something as below in my query
select * from table a
where a.id in(select id, max(date) from table a group by id)
I am getting error here , as IN is equivalent to = .
how to do it?
example :
id
date
1
2022-31-01
1
2022-21-03
2
2022-01-01
2
2022-02-01
I need to get only one record based on date(max). The table has more columns than just id and date
so I need to something like this in snowflake
select * from table a
where id in(select id,max(date) from table a group by id)
```-----------------------
All solutions are working , if i select from table .
but i have case statement in view where duplicate records are coming
example :
create or replace view v_test
as
select * from
(
select id,lastdatetime,*,
case when start_date < timestamp and timestamp < end
and move_date = '9999-12-31' then 'Y'
else 'N' end as IND
from table a
) a
so if any one select view where IND= 'Y', more than 1 records are coming
what i want is to select latest records for ID where IND='Y' and max(lastdatetime)
how to incorporate this logic in view?

Answer 1

I think you are trying to get the latest record for each id?
select *
from table a
qualify row_number() over (partition by id order by date desc) = 1

Answer 2

So if we look at your sub-select:
using this "data" for the examples:
with data (id, _date) as (
select column1, to_date(column2, 'yyyy-dd-mm') from values
(1, '2022-31-01'),
(1, '2022-21-03'),
(2, '2022-01-01'),
(2, '2022-02-01')
)
select id, max(_date)
from data
group by 1;
it gives:
ID
MAX(_DATE)
1
2022-03-21
2
2022-01-02
which makes it seem you want the "the last date, per id"
which can classically (ansi sql) be written:
select d.*
from data as d
join (
select
id,
max(_date) as max_date
from data
group by 1
) as c
on d.id = c.id and d._date = c.max_date
;
ID
_DATE
1
2022-03-21
2
2022-01-02
which gives you "all the rows values". BUT if you have many rows with the same last date, you will get those, in the output.
Another methods is to use a ROW_NUMBER to pick one and only one row, which is the style of answer Mike has given:
with data (id, _date, extra) as (
select column1, to_date(column2, 'yyyy-dd-mm'), column3 from values
(1, '2022-31-01', 'extra_a'),
(1, '2022-21-03', 'extra_b_double_a'),
(1, '2022-21-03', 'extra_b_double_b'),
(2, '2022-01-01', 'extra_c'),
(2, '2022-02-01', 'extra_d')
)
select *
from data
qualify row_number() over (partition by id order by _date desc) =1 ;
gives:
ID
_DATE
EXTRA
1
2022-03-21
extra_b_double_a
2
2022-01-02
extra_d
now if you want the "all rows of the last day" you method works, albeit the QUALIFY/ROW_NUMBER is faster. You can use RANK
with data (id, _date, extra) as (
select column1, to_date(column2, 'yyyy-dd-mm'), column3 from values
(1, '2022-31-01', 'extra_a'),
(1, '2022-21-03', 'extra_b_double_a'),
(1, '2022-21-03', 'extra_b_double_b'),
(2, '2022-01-01', 'extra_c'),
(2, '2022-02-01', 'extra_d')
)
select *
from data
qualify dense_rank() over (partition by id order by _date desc) =1 ;
ID
_DATE
EXTRA
1
2022-03-21
extra_b_double_a
1
2022-03-21
extra_b_double_b
2
2022-01-02
extra_d
Now the last thing that it almost seems you are asking for, is "how do find the ID with the most recent data (here 1) and get all rows for that"
with data (id, _date, extra) as (
select column1, to_date(column2, 'yyyy-dd-mm'), column3 from values
(1, '2022-31-01', 'extra_a'),
(1, '2022-21-03', 'extra_b_double_a'),
(1, '2022-21-03', 'extra_b_double_b'),
(2, '2022-01-01', 'extra_c'),
(2, '2022-02-01', 'extra_d')
)
select *
from data
qualify id = last_value(id) over (order by _date);

Answer 3

Here is an example of how to use the in operator with a subquery:
select * from table1 t1 where t1.id in (select t2.id from table2 t2);

Answer 4

Usage of IN is possible to match on both columns:
select *
from tab AS a
where (a.id, a.date) in (select id, max(date) from tab group by id);
For sample data:
CREATE TABLE tab (id, date)
AS
SELECT column1, to_date(column2, 'yyyy-dd-mm')
FROM VALUES
(1, '2022-31-01'),
(1, '2022-21-03'),
(2, '2022-01-01'),
(2, '2022-02-01');
Output: