I have two tables:
foos:
id
f_name
1
xxx
2
yyy
3
zzz
foo_bars:
id
foo_id
active
1
1
false
2
1
false
3
1
false
4
2
true
5
2
false
6
2
true
7
3
false
7
3
true
Each foo should have each an active foo_bar, and only one. Because of a poorly designed process, it sometimes happened that either more than one foo_bar was set to active=true, or that no foo_bar was set to active. Neither is a valid scenario.
I need to find those rows on foos where the linked foo_bars rows with active are != 1.
E.g. in the above scenario I'd like to get:
1,xxx
2,yyy
Can I accomplish this with a single query?
I think this would be a good use of the HAVING clause in a GROUP BY query:
select
f.id, f.f_name
from foos f
left join foo_bars b on f.id = b.foo_id
group by
f.id, f.f_name
having
count (*) filter (where b.active) != 1
Related
I have table A:
id
1
2
3
4
5
and table B:
id
2
3
4
I left join A and B:
id id
1 NULL
2 2
3 3
4 4
5 NULL
And how can I get a new column like this:
id id flag
1 NULL 0
2 2 1
3 3 1
4 4 1
5 NULL 0
Generally speaking, I want all rows in A but not in B to be flaged as 0 and want all rows in both tables to be flaged as 1. How can I achieve that? Better not use CTE.
This is just a CASE expression:
CASE WHEN B.id IS NULL THEN 0 ELSE 1 END AS flag
Alternatively, you could use an IIF (which is shorthand CASE expression):
IIF(b.id IS NULL, 0,1)
I would recommend using exists:
select a.*,
(case when exists (select 1 from b where b.id = a.id
then 1 else 0
end) as flag
from a;
The purpose of using exists instead of left join is that you are guaranteed to not get duplicate rows -- even if ids are duplicated in b. That is a nice guarantee.
From a performance perspective, the two should be similar, but it is possible that the case is an iota faster.
A temp table has 700+ records with a PK. 12 columns contain Id values from lookup tables. Each lookup table has 4-8 records in it. How can I get a record count for each Id value in table LookupA that has a relationship via the PK to Id values in every other lookup table? Each lookup value in each lookup table needs to compared for a record count to every other lookup table and value.
I can write a SQL statement to get specific values for specific columns, but that's a long exercise and will slow down the proc.
Here's a sample of the data.
PK LookupA LookupB LookupC
1 1 1 3
2 1 2 3
3 1 3 2
4 2 4 2
5 4 1 1
6 3 2 1
7 2 3 3
8 4 4 3
9 4 3 2
10 1 1 2
The results need to compare LookupA with LookupB and LookupC to get a row count.
Table Value LookupB 1 2 3 4 LookupC 1 2 3
LookupA 1 2 1 1 0 0 2 2
2 0 0 1 1 0 1 1
3 0 1 0 0 1 0 0
4 1 0 1 1 1 1 1
Then LookupB would be compared to LookupA and LookupC.
And LookupC would be compared to LookupA and LookupB.
With this code you can get the numbers for all combinations of A,B and C in pairs:
select 'A-B' as Combination, LookupA, LookupB, count(*) as NumRecords
from table
group by Combination,LookupA, LookupB
UNION
select 'A-C' as Combination, LookupA, LookupC, count(*) as NumRecords
from table
group by Combination,LookupA, LookupC
UNION
select 'B-C' as Combination, LookupB, LookupC, count(*) as NumRecords
from table
group by Combination,LookupB, LookupC
After this, if you want to see all the values for LookupA comparing to B and C just
look for Combinations A-B and A-C
If I understand correctly, your temp table contains foreign keys to other tables, so why not simply use joins? Something like this.
SELECT COUNT(DISTINCT lookupA.id) as CountA
, COUNT(DISTINCT lookupB.id) as CountB
, etc...
FROM #temp_table t
LEFT OUTER JOIN lookupA a on a.id = t.lookupA
LEFT OUTER JOIN lookupB b on b.id = t.lookupB
...etc
I would suggest reviewing the design if possible. Having so many small tables complicates things, is it not possible to consolidate this and just have one lookup table? You could have an additional field "LookupType" and all the lookups could be in the same place which would make retrieval much simpler.
I used a slight derivative of the statement below without any UNIONs to get me where I wanted to go.
/*
select 'A-B' as Combination, LookupA, LookupB, count(*) as NumRecords
from table
group by Combination, LookupA, LookupB
*/
I used a variable and a WHILE loop to place the various summaries where they need to be.
So I have
a table that stores asymmetrical connections between two persons
(like a Twitter follow; not like a Facebook friend) and
a table that stores a person's affiliations to various groups
My task is to find, for each asymmetrical relationship, the number of affiliations shared between the "from person" and the "to person".
I made this brute force solution, but I'm wondering if brighter minds could come up with something more efficient.
select frm01.from_person_id, frm01.to_person_id, count(*) num_affl
from
(
select lnk.from_person_id, lnk.to_person_id, ga.grp_id from_grp_id
from links lnk
left outer join grp_affl ga on lnk.from_person_id = ga.person_id
group by lnk.from_person_id, lnk.to_person_id, grp_id
) frm01
inner join
(
select lnk.from_person_id, lnk.to_person_id, ga.grp_id to_grp_id
from links lnk
left outer join grp_affl ga on lnk.to_person_id = ga.person_id
group by lnk.from_person_id, lnk.to_person_id, grp_id
) to01
on (
frm01.from_person_id = to01.from_person_id
and frm01.to_person_id = to01.to_person_id
and frm01.from_grp_id = to01.to_grp_id
)
group by frm01.from_person_id, frm01.to_person_id;
Using ANSI SQL on Netezza (which doesn't allow correlated subqueries).
TIA!
Edited to add table schema:
table lnk:
from_person_id to_person_id
1 4
2 5
3 6
4 2
5 3
table grp_affl:
person_id grp_id
1 A
1 B
1 C
2 A
3 B
4 C
5 A
5 B
5 C
6 A
expected output:
from_person_id to_person_id num_affl
1 4 1
2 5 1
3 6 0
4 2 0
5 3 1
Persons 1 & 4 have 1 affiliation in common (C), 2 & 5 have A in common, 5 & 3 have B in common. 3 & 6 have nothing in common. Likewise 4 & 2.
You can do this with aggregation and the right joins:
select pairs.from_person, pairs.to_person, count(*)
from links pairs join
grp_affil fromga
on fromga.person_id = pairs.from_person join
grp_affil toga
on toga.person_id = pairs.to_person and
toga.grp_id = fromga.grp_id
group by pairs.from_person, pairs.to_person;
The joins bring in the groups. The last condition only brings in matching groups between the two persons. The final group by counts them.
Essentially what I'm trying to do is count the number of rows something doesn't exist in an audit/history table. I'd like the following query to return a count of one per detail. Currently it gives me one per row in the history table.
--Detail Table
ID DETAIL_GROUP
1 A
2 B
3 B
--Detail History Table
DETAIL_ID_FK VALUE1
1 NOT_MATCH
1 NOT_MATCH
2 MATCH
2 NOT_MATCH
3 MATCH
3 NOT_MATCH
SELECT D.DETAIL_GROUP, COUNT(*)
FROM DETAIL D
WHERE (NOT EXISTS(
SELECT NULL
FROM DETAIL_HISTORY HI
WHERE HI.D_ID_FK = D.ID
AND HI.VALUE1 = 'MATCH'))
GROUP BY D.DETAIL_GROUP;
I'd like to see the following result:
DETAIL_GROUP COUNT(*)
A 1
but I'm receiving the following result:
DETAIL_GROUP COUNT(*)
A 2
Thank you in advance for any assistance provided.
Assuming that your detail table is as follows:
D_ID VALUE1
1 MATCH
1 NOT_MATCH
2 MATCH
2 NOT_MATCH
3 MATCH
3 NOT_MATCH
The below query:
SELECT d.detail_group, count(*)
FROM detail d
JOIN detail_history dh ON dh.d_id = d.id
WHERE dh.value1 = 'MATCH'
GROUP BY d.detail_group
Would produce:
DETAIL_GROUP COUNT(*)
A 1
B 2
The above query creates the groups matching the ids and then goes into each group and restricts the items based on value1.
I have two intermediate result sets in a create view statement. The result sets are derived from two different join paths and I need to union them. But it doesn't stop here. Since the ID column needs to be unique, I will then need the rows in result set 2 that contains the same IDs as the first result set to overwrite the same rows in the first result set.
Let me illustrate this here:
Result set 1
ID Value
------------
1 a
3 a
5 a
6 a
7 a
8 a
Result Set 2
ID Value
------------
2 b
4 b
5 b
7 b
9 b
10 b
End result set
ID value
------------
1 a
2 b
3 a
4 b
5 b
6 a
7 b
8 a
9 b
10 b
I am not sure how to approach this. Union/except/intersect will create duplicate ids, so that's no good.
SELECT COALESCE(set2.ID, set1.ID) AS ID,
CASE WHEN set2.ID IS NULL THEN set1.Value ELSE set2.Value END AS Value
FROM set1
FULL JOIN set2
ON set1.ID = set2.ID
Try deleting elements from result set 1 where id exists in result set 2 before union all.