In table I have used jsonb to store multiple values in json array. now i want to write a query where day is monday. [{'day':'monday','time':"8 am"},{'day':'tuesday','time':"8 am"}{'day':'monday','time':"11 am"},{'day':'friday','time':"8 am"}]
Query:
SELECT array_to_json(array_agg(j))
FROM demo t, jsonb_array_elements(t.di_item ) j
WHERE j->>'day' = 'monday'
Result:
[{'day':'monday','time':"8 am"},{'day':'monday','time':"11 am"},{'day':'monday','time':"8
am"},{'day':'monday','time':"11 am"}]
Expected:
[{'day':'monday','time':"8 am"},{'day':'monday','time':"11 am"}]
One value getting two times.
First: no need to aggregate the json objects as an array, and then convert it to a json array, you can use json[b]_agg() directly. Then: use distinct to avoid duplicates.
SELECT jsonb_agg(distinct j)
FROM demo t
CROSS JOIN LATERAL jsonb_array_elements(t.di_item) j
WHERE j->>'day' = 'monday'
Related
I have an array column in hive which will be having 7 numbers.
For Ex: [32,4,0,43,23,0,1]
I want my output to be [32,4,43,23,1] (with all the zero elements removed)
Someone help me to accomplish this?
Explode array, filter, collect again.
Demo:
with mydata as (
select array(32,4,0,43,23,0,1) as initial_array
)
select initial_array, collect_set(element) as result_array
from
(
select initial_array, e.element
from mydata
lateral view outer explode(initial_array)e as element
) s
where element != 0
group by initial_array
Result:
initial_array result_array
[32,4,0,43,23,0,1] [32,4,43,23,1]
I'm trying to group BigQuery columns using an array like so:
with test as (
select 1 as A, 2 as B
union all
select 3, null
)
select *,
[A,B] as grouped_columns
from test
However, this won't work, since there is a null value in column B row 2.
In fact this won't work either:
select [1, null] as test_array
When reading the documentation on BigQuery though, it says Nulls should be allowed.
In BigQuery, an array is an ordered list consisting of zero or more
values of the same data type. You can construct arrays of simple data
types, such as INT64, and complex data types, such as STRUCTs. The
current exception to this is the ARRAY data type: arrays of arrays are
not supported. Arrays can include NULL values.
There doesn't seem to be any attributes or safe prefix to be used with ARRAY() to handle nulls.
So what is the best approach for this?
Per documentation - for Array type
Currently, BigQuery has two following limitations with respect to NULLs and ARRAYs:
BigQuery raises an error if query result has ARRAYs which contain NULL elements, although such ARRAYs can be used inside the query.
BigQuery translates NULL ARRAY into empty ARRAY in the query result, although inside the query NULL and empty ARRAYs are two distinct values.
So, as of your example - you can use below "trick"
with test as (
select 1 as A, 2 as B union all
select 3, null
)
select *,
array(select cast(el as int64) el
from unnest(split(translate(format('%t', t), '()', ''), ', ')) el
where el != 'NULL'
) as grouped_columns
from test t
above gives below output
Note: above approach does not require explicit referencing to all involved columns!
My current solution---and I'm not a fan of it---is to use a combo of IFNULL(), UNNEST() and ARRAY() like so:
select
*,
array(
select *
from unnest(
[
ifnull(A, ''),
ifnull(B, '')
]
) as grouping
where grouping <> ''
) as grouped_columns
from test
An alternative way, you can replace NULL value to some NON-NULL figures using function IFNULL(null, 0) as given below:-
with test as (
select 1 as A, 2 as B
union all
select 3, IFNULL(null, 0)
)
select *,
[A,B] as grouped_columns
from test
I Need to extract values from string with Postgresql
But for my special scenario - if an element value is null i want to remove it and bring the next element 1 index closer.
e.g.
assume my string is: "a$$b"
If i will use
select string_to_array('a$$b','$')
The result is:
{a,,b}
If Im trying
SELECT unnest(string_to_array('a__b___d_','_')) EXCEPT SELECT ''
It changes the order
1.d
2.a
3.b
order changes which is bad for me.
I have found a other solution with:
select array_remove( string_to_array(a||','||b||','||c,',') , '')
from (
select
split_part('a__b','_',1) a,
split_part('a__b','_',2) b,
split_part('a__b','_',3) c
) inn
Returns
{a,b}
And then from the Array - i need to extract values by index
e.g. Extract(ARRAY,2)
But this one seems to me like an overkill - is there a better or something simpler to use ?
You can use with ordinality to preserve the index information during unnesting:
select a.c
from unnest(string_to_array('a__b___d_','_')) with ordinality as a(c,idx)
where nullif(trim(c), '') is not null
order by idx;
If you want that back as an array:
select array_agg(a.c order by a.idx)
from unnest(string_to_array('a__b___d_','_')) with ordinality as a(c,idx)
where nullif(trim(c), '') is not null;
I am trying to execute below query:
select * from trgdms.src_stm where trim(src_stm_code) in (select concat (concat('''', trim(replace(processed_src_sys_cd,',',''','''))),'''' ) from trgdms.batch_run_log where src_stm_cd_or_hub_cd='CTR' and file_process_dt='2015-06-19' and batch_id=42);
the src_stm_code column of table trgdms.src_stm have values like T19,T68,T73 etc. When I run the inner query alone i do get the correct result:
select concat (concat('''', trim(replace(processed_src_sys_cd,',',''','''))),'''' ) from trgdms.batch_run_log where src_stm_cd_or_hub_cd='CTR' and file_process_dt='2015-06-19' and batch_id=42
Result: 'T19','T68','T73'
Wondered if anyone has used something similar in db2?
Remove the concat part from the inner query. When you concatenate values, the list of values generated will be treated as a string and the query doesn't return any results.
select * from trgdms.src_stm where trim(src_stm_code)
in (select trim(replace(processed_src_sys_cd,',',''',''')) from trgdms.batch_run_log
where src_stm_cd_or_hub_cd='CTR' and file_process_dt='2015-06-19' and batch_id=42);
I have the following data:
name id url
John 1 someurl.com
Matt 2 cool.com
Sam 3 stackoverflow.com
How can I write an SQL statement in Postgres to select this data into a multi-dimensional array, i.e.:
{{John, 1, someurl.com}, {Matt, 2, cool.com}, {Sam, 3, stackoverflow.com}}
I've seen this kind of array usage before in Postgres but have no idea how to select data from a table into this array format.
Assuming here that all the columns are of type text.
You cannot use array_agg() to produce multi-dimensional arrays, at least not up to PostgreSQL 9.4.
(But the upcoming Postgres 9.5 ships a new variant of array_agg() that can!)
What you get out of #Matt Ball's query is an array of records (the_table[]).
An array can only hold elements of the same base type. You obviously have number and string types. Convert all columns (that aren't already) to text to make it work.
You can create an aggregate function for this like I demonstrated to you here before.
CREATE AGGREGATE array_agg_mult (anyarray) (
SFUNC = array_cat
,STYPE = anyarray
,INITCOND = '{}'
);
Call:
SELECT array_agg_mult(ARRAY[ARRAY[name, id::text, url]]) AS tbl_mult_arr
FROM tbl;
Note the additional ARRAY[] layer to make it a multidimensional array (2-dimenstional, to be precise).
Instant demo:
WITH tbl(id, txt) AS (
VALUES
(1::int, 'foo'::text)
,(2, 'bar')
,(3, '}b",') -- txt has meta-characters
)
, x AS (
SELECT array_agg_mult(ARRAY[ARRAY[id::text,txt]]) AS t
FROM tbl
)
SELECT *, t[1][3] AS arr_element_1_1, t[3][4] AS arr_element_3_2
FROM x;
You need to use an aggregate function; array_agg should do what you need.
SELECT array_agg(s) FROM (SELECT name, id, url FROM the_table ORDER BY id) AS s;