I have a database table with data similar to this.
create table DataTable (
name text,
value number
)
insert into DataTable values
('A', 1),('A', 2),('B', 3),('Other', 5),('C', 1);
And i have another table
create table "group" (
name text,
default boolean
)
insert into "group" values
('A', false),('B', false),('Other', true);
I want to group the data in the first table based on the defined groups in the second table.
Expected output
Name | sum
A | 3
B | 3
Other | 6
Right now I'm using this query:
select coalesce(g.name, (select name from group where default = true)) name
sum(dt.value)
from DataTable dt
left join group g on dt.name = g.name
group by 1
This works but can cause performance tips in some situations. Any better way to do this?
Related
Iam trying to extract a list of operation that was inactive in each month :
table 1 "all_opreration" is containing the whole list of operation id
table all_operation
the second table "active_operation" is containing the operations that was active on the specified month
table active operation
So I want to get "inactive operation" by month (for each month the operation that was not in active_operation table
==> Wished table :
wished table inactive operation
I have tried several ways but without success
Thank you in advance
You just need to left join and check the the right side is NULL. You will need to expand your all_operations to have all dates but this can be done with a cross join. Like this:
Set up:
create table all_ops (op_id varchar(32));
insert into all_ops values ('A'), ('B'), ('C');
create table active_ops (month date, op_id varchar(32));
insert into active_ops values ('2021-10-01', 'A'),
('2021-10-01', 'B'),
('2021-07-01', 'C');
Find the missing data / id pairs:
select l.month, l.op_id
from (
select month, op_id
from all_ops
cross join (select distinct month from active_ops) m
) l
left join active_ops r
on l.op_id = r.op_id and l.month = r.month
where r.op_id is null;
I have two tables a and b. Where main table is 'a' where I want to select from and table 'b' is for filtering.
Below is sample table with some data.
create table a (
id varchar primary key,
name varchar,
p varchar[]
);
insert into a (id, name, p) values
('1', 'v1', array['p1']),
('2', 'v2', array['p1','p2']),
('3', 'v3', array['p2','p3']);
create table b (
p varchar,
x varchar
);
insert into b(p, x) values
('p1', 'x1'),
('p2', 'x2'),
('p3', 'x1'),
('p3', 'x3'),
('p1', 'x2');
I want only one row from table a based on join on column p and filter on x. I tried few options, it works when I have one to one record in a and b but when I have one to many then I get multiple records.
select a.* from a,b where b.p=any(a.p) and b.x='x2';
Output I get is:
id name p
-----------------
1 v1 p1
2 v2 p1,p2
2 v2 p1,p2
3 v3 p2,p3
What I want is
id name p
-----------------
1 v1 p1
2 v2 p1,p2
3 v3 p2,p3
Also I am expecting table 'a' to have millions of rows and 'b' will have only few, so query has to be perform effectively.
As you only want columns from table a use an exists condition rather than a join:
select a.*
from a
where exists (select *
from b
where b.p = any(a.p)
and b.x='x2');
That will however be quite hard to optimize.
Another option - if not too many rows match the join criteria - is to apply a distinct on the result of the join.
In that case a GIN index on the array column can be used:
create index on a using gin (p);
select distinct a.*
from a
join b on a.p #> array[b.p]
where b.x= 'x2';
I'm trying to do multiple update, but it works only for the first row.
I have table "users" with 2 records:
create table users
(
uid serial not null
constraint users_pkey
primary key,
balance numeric default 0 not null
);
INSERT INTO public.users (uid, balance) VALUES (2, 100);
INSERT INTO public.users (uid, balance) VALUES (1, 100);
I try to UPDATE user "1" twice with the query, but it update only one time:
balance for user "1" become "105", not "115"
update users as u
set balance = balance + c.bal
from (values (1, 5),
(1, 10)
) as c(uid, bal)
where c.uid = u.uid;
Why it not updated for all rows from subquery?
The postgresql documentation gives no reason for this behaviour but does specify it.
Relevant quote
When a FROM clause is present, what essentially happens is that the
target table is joined to the tables mentioned in the from_list, and
each output row of the join represents an update operation for the
target table. When using FROM you should ensure that the join produces
at most one output row for each row to be modified. In other words, a
target row shouldn't join to more than one row from the other
table(s). If it does, then only one of the join rows will be used to
update the target row, but which one will be used is not readily
predictable.
Use a SELECT with a GROUP BY to combine the rows before performing the update.
You need to aggregate in the inner query before joining:
update users as u
set balance = balance + d.bal
from (
select uid, sum(bal) bal
from ( values (1, 5), (1, 10) ) as c(uid, bal)
group by uid
) d
where d.uid = u.uid;
Demo on DB Fiddle:
| uid | balance |
| --- | ------- |
| 2 | 100 |
| 1 | 115 |
I have some interesting data, I'm trying to query however I cannot get the syntax correct. I have a temporary table (temp_id), which I've filled with the id values I care about. In this example it is only two ids.
CREATE TEMPORARY TABLE temp_id (id bigint PRIMARY KEY);
INSERT INTO temp_id (id) VALUES ( 1 ), ( 2 );
I have another table in production (let's call it foo) which holds multiples those ids in a single cell. The ids column looks like this (below) with ids as a single string separated by "|"
ids
-----------
1|9|3|4|5
6|5|6|9|7
NULL
2|5|6|9|7
9|11|12|99
I want to evaluate each cell in foo.ids, and see if any of the ids in match the ones in my temp_id table.
Expected output
ids |does_match
-----------------------
1|9|3|4|5 |true
6|5|6|9|7 |false
NULL |false
2|5|6|9|7 |true
9|11|12|99 |false
So far I've come up with this, but I can't seem to return anything. Instead of trying to create a new column does_match I tried to filter within the WHERE statement. However, the issue is I cannot figure out how to evaluate all the id values in my temp table to the string blob full of the ids in foo.
SELECT
ids,
FROM foo
WHERE ids = ANY(SELECT LISTAGG(id, ' | ') FROM temp_ids)
Any suggestions would be helpful.
Cheers,
this would work, however not sure about performance
SELECT
ids
FROM foo
JOIN temp_ids
ON '|'||foo.ids||'|' LIKE '%|'||temp_ids.id::varchar||'|%'
you wrap the IDs list into a pair of additional separators, so you can always search for |id| including the first and the last number
The following SQL (I know it's a bit of a hack) returns exactly what you expect as an output, tested with your sample data, don't know how would it behave on your real data, try and let me know
with seq AS ( # create a sequence CTE to implement postgres' unnest
select 1 as i union all # assuming you have max 10 ids in ids field,
# feel free to modify this part
select 2 union all
select 3 union all
select 4 union all
select 5 union all
select 6 union all
select 7 union all
select 8 union all
select 9 union all
select 10)
select distinct ids,
case # since I can't do a max on a boolean field, used two cases
# for 1s and 0s and converted them to boolean
when max(case
when t.id in (
select split_part(ids,'|',seq.i) as tt
from seq
join foo f on seq.i <= REGEXP_COUNT(ids, '|') + 1
where tt != '' and k.ids = f.ids)
then 1
else 0
end) = 1
then true
else false
end as does_match
from temp_id t, foo
group by 1
Please let me know if this works for you!
I would like to know an efficient to way to fetch the data in the following case.
There are two tables say Table1 and Table2 having two common field say contry and pincode and other table "Table3" having key fields of first two tables (DNO, MPNO).
Here is the little glitch, In table3 data, if it is having DNO it wont have MPNO
So when in the selection screen(Pic no2) if the use enter any thing, result should be as follows
**MFID | DNO | MPNO | COUNTRY | PINCODE**
----------
00001 | 10011 | novalue | IN | 4444
00002 | Novalue | 1200 | IN | 5555
00003 | 300 | novalue | US | 9999
( as you can observe if DNO present no MPNO , vice versa )
Please have a look at the pictures for a clear picture :-)
Table Relation:
Selection screen with select options:
The code shouldn't be long.
PSEUDO CODE:
Select queries:
Select * from table3 into it_table3.
Select * from table1 FOR ALL ENTRIES IN it_table3 INTO it_table1
WHERE dno = table3-dno.
Select * from table2 FOR ALL ENTRIES IN it_table3 INTO it_table2
WHERE mpno = table3-mpno.
Loop at internal table 3 and build final table.
LOOP at it_table3 into wa_table3.
IF wa_table3-dno IS NOT INITIAL.
READ it_table1 where dno = wa_table3-dno.
ELSE.
READ it_table2 where mpno = wa_table3-mpno.
ENDIF.
ENDLOOP.
Hope this was the answer you were hoping to find!
Building of efficient select will require information about obligatory fields in your selection screen, as well as about alleged production size of all 3 tables. However, without this information let's assume that table1 and table2 are reference tables and table3 is a transaction table, as onr can assume from their structure. It would be sensible to build selection in a following way:
Selecting data from reference tables. As you said fields DNO/MPNO are mutually exclusive then there will be no hits of country/pincode pair in both reference tables, so JOIN is useless here. However we can merge 2 result sets in single itab without any constraints' violations.
TYPES: BEGIN OF tt_result,
dno TYPE table1-dno,
mpno TYPE table2-mpno,
country TYPE table1-country,
pincode TYPE table1-pincode,
...other field from table3
END OF tt_result.
DATA: itab_result TYPE tt_result.
SELECT dno
FROM table1
INTO CORRESPONDING FIELDS OF TABLE itab_result
WHERE pincode IN so_pincode
AND country IN so_country.
SELECT mpno
FROM table2
APPENDING CORRESPONDING FIELDS OF TABLE itab_result
WHERE pincode IN so_pincode
AND country IN so_country.
FOR ALL ENTRIES addition allows specifying the same table in FOR ALL ENTRIES clause and in INTO clause, so we can fill our result table with absent table3 data by DNO/MPNO key.
SELECT *
FROM table3
INTO CORRESPONDING FIELDS OF TABLE itab_result
FOR ALL ENTRIES IN itab_result
ON itab_result~dno = itab3~dno
AND itab_result_mpno = itab3~mpno.