I am migrating from oracle to postgres and I don't know how to make a recursive query
Here is an example data set:
id
id_parent
name
1
0
aa
2
0
aa
3
1
aa
4
3
aa
5
3
aa
6
2
aa
7
6
aa
For id = 3, I want to get
id
3
4
5
for id =1
id
1
3
4
5
with this I have all but I don't know how to filter by id:
SELECT id FROM (
with recursive cat as (
select * from table
union all
select table.*
from table
join cat on cat.id_parent = table.id
)
select * from cat order by id
)
as listado where id != '0' group by id
There is no need of using sub-query. You just need to fix your recursive query only as -
WITH RECURSIVE cat (id, id_parent) as
(
SELECT id, id_parent
FROM table
WHERE id = 1
UNION ALL
SELECT d.id, d.id_parent
FROM table d
JOIN cat ON cat.id = d.id_parent
)
SELECT id
FROM cat
ORDER BY id;
Demo.
Related
Given that I am using Redshift, how would I get the counts for a query that asks:
Given table A and table B, give me all the count of values in Table A for that grouping that aren't in table B;
So if table A and B look like:
Table A
Id | Value
==========
1 | "A"
1 | "B"
2 | "C"
And table B:
Id | Value
==========
1 | "A"
1 | "D"
2 | "C"
I would want:
Id | Count
==========
1 | 1
2 | 0
You can use left join and group by:
select a.id, sum( (b.id is null)::int )
from a left join
b
on a.id = b.id and a.value = b.value
group by a.id;
Use except and subquery
with a as
(
select 1 as id, 'A' as v
union all
select 1,'B'
union all
select 2,'C'
),b as
(
select 1 as id, 'A' as v
union all
select 1,'D'
union all
select 2,'C'
), c as
(
select id,v from a except select id,v from b
)
select id,sum ( (select count(*) from c where c.id=a.id and c.v=a.v))
from a group by id
output
id cnt
1 1
2 0
online demo which will work in redshift
I have 2 tables both structured as (id, views)
Table 1:
id views
A 1
B 2
B 3
C 3
C 4
D 4
Table 2:
id views
C 1
D 3
D 4
E 5
E 7
F 8
I'm looking to sum views of ids that are both in table 1 and 2 (id C and D) in this case so the output would be:
Table 3:
id views
C 8
D 11
You could use the following query in your case :
select a.id,sum(a.views) from ( select * from table1 union table2 ) as a group by id;
select id,sum(views) from (select * from table1 union all select * from table2)a where a.id="C" or a.id="D" group by id;
I want to fetch the records in order passed for IN condition.
select * from table where id in(6,3,7,1);
is returning the rows as
id name
1 abc
3 xy
6 ab
7 ac
but I want to display the records in same orders as ids passed in condition in Oracle
id name
6 ab
3 xy
7 ac
1 abc
Please help me in fetching the records in same order as in condition ids in oracle. The values in IN condition may change dynamically.
You can do this with a case statement in the order by clause or using a join.
select *
from table
where id in(6,3,7,1)
order by (case id when 6 then 1 when 3 then 2 when 7 then 3 when 1 then 4 end);
Or:
with ids as (
select 6 as id, 1 as ordering from dual union all
select 3 as id, 2 as ordering from dual union all
select 7 as id, 3 as ordering from dual union all
select 1 as id, 4 as ordering from dual
)
select *
from table t join
ids
on t.ids = ids.id
order by ids.ordering;
Note that you don't need the in in this case, because the join does the filtering.
you can use trick
select * from table where id in(6,3,7,1) order by case when id = 6 then 1
id = 3 then 2
id = 7 then 3
id = 1 then 4
end
I am working on a simple problem and wanted to solve it using SQL. I am having 3 tables Category, Item & a relational table CategoryItem. I need to return count of items per category but the twist is Categories are arranged in Parent-Child relationships and the count of items in child categories should be added to the count in its parent Category. Please consider the sample data below and the expected resultset using SQL.
Id Name ParentCategoryId
1 Category1 Null
2 Category1.1 1
3 Category2.1 2
4 Category1.2 1
5 Category3.1 3
ID CateoryId ItemId
1 5 1
2 4 2
3 5 2
4 3 1
5 2 3
6 1 1
7 3 2
Result:
CategoryNAme Count
Category1 7
Category1.1 5
Category2.1 4
Category1.2 1
Category3.1 2
I can do it in my business layer but performance its not optimal because of size of data. I am hoping if I can do it in data layer, I would be able to improve performance greatly.
Thanks in Advance for your reply
your tables and sample data
create table #Category(Id int identity(1,1),Name Varchar(255),parentId int)
INSERT INTO #Category(Name,parentId) values
('Category1',null),('Category1.1',1),('Category2.1',2),
('Category1.2',1),('Category3.1',3)
create table #CategoryItem(Id int identity(1,1),categoryId int,itemId int)
INSERT INTO #CategoryItem(categoryId,itemId) values
(5,1),(4,2),(5,2),(3,1),(2,3),(1,1),(3,2)
create table #Item(Id int identity(1,1),Name varchar(255))
INSERT INTO #Item(Name) values('item1'),('item2'),('item3')
Checking for all childs of parent by Recursive Commom Table Expressions
;WITH CategorySearch(ID, parentId) AS
(
SELECT ID, ID AS ParentId FROM #Category
UNION ALL
SELECT CT.Id,CS.parentId FROM #Category CT
INNER JOIN CategorySearch CS ON CT.ParentId = CS.ID
)
select * from CategorySearch order by 1,2
Output: All child records against parent
ID parentId
1 1
2 1
3 1
4 1
5 1
2 2
3 2
5 2
3 3
5 3
4 4
5 5
Final query for your result, count all items for category and its children categories.
;WITH CategorySearch(ID, parentId) AS
(
SELECT ID, ID AS ParentId FROM #Category
UNION ALL
SELECT CT.Id,CS.parentId FROM #Category CT
INNER JOIN CategorySearch CS ON CT.ParentId = CS.ID
)
SELECT CA.Name AS CategoryName,count(itemId) CountItem
FROM #Category CA
INNER JOIN CategorySearch CS ON CS.ParentId = CA.id
INNER JOIN #CategoryItem MI ON MI.CategoryId =CS.ID
GROUP BY CA.Name
Output:
CategoryName CountItem
Category1 7
Category1.1 5
Category1.2 1
Category2.1 4
Category3.1 2
with help of CTE (common table expression) with recursion, you could achieve what you are looking for.
see Microsoft help for more details retated to recursive CTEs: CTE MS SQL 2008 +
hereby you could find complete example, with your sample data:
-- tables definition
SELECT 1 as id, 'cat1' as [name],NULL as id_parent
into cat
union
select 2, 'cat1.1', 1
union
select 3, 'cat2.1', 2
union
select 4, 'cat1.2', 1
union
select 5, 'cat3.1', 3
select 1 as id , 5 as id_cat, 1 as id_item
iNTO item
UNION
select 2, 4, 2
UNION
select 3, 5, 2
UNION
select 4, 3, 1
UNION
select 5, 2, 3
UNION
select 6, 1, 1
UNION
select 7, 3, 2
-- CTE to get desired result
with childs
as
(
select c.id, c.id_parent
from cat c
UNION ALL
select s.id, p.id_parent
from cat s JOIN childs p
ON (s.id_parent=p.id)
),
category_count
AS
(
SELECT c.id, c.name, count(i.id) as items
from cat c left outer join item i
on (c.id=i.id_cat)
GROUP BY c.id,c.name
),
pairs
AS
(
SELECT id, ISNULL(id_parent,id) as id_parent
FROM childs
)
select p.id_parent, n.name, sum(items)
from pairs p JOIN category_count cc
ON (p.id=cc.id)
join cat n ON (p.id_parent=n.id)
GROUP by p.id_parent ,n.name
ORDER by 1;
I have a table like below
CAccountID CID NetworkID
1 1 1
2 1 2
3 2 1
4 2 2
5 2 3
6 3 1
7 3 2
8 3 3
9 4 1
10 4 2
I need a query to select all CID having all 3 NetworkID(1,2,3) and don't need to display only 1 and 2 NetworkID.
Output should be like below,
CAccountID CID NetworkID
3 2 1
4 2 2
5 2 3
6 3 1
7 3 2
8 3 3
You can use GROUP BY with JOIN :
select t.*
from table t inner join
( select cid
from table
where NetworkID in (1,2,3)
group by cid
having count(distinct NetworkID) = 3
) tt
on tt.cid = t.cid;
Try this:
select * from my_table t
where exists(select 1 from my_table
where CID = t.CID and NetworkID in (1,2,3)
group by CID
having count(*) = 3)
Try this:
select * from <<tablename>> where cid in(select cid from <<tablename>> group by cid having count(*)=3).
Here the subquery will return you all thouse cid which have 3 rows in your table.
Or if you have more network ids then use of INTERSECT operator can be helpful:
select * from <<tablename>> where cid in (
select cid from <<tablename>> where NetworkID=1
INTERSECT
select cid from <<tablename>> where NetworkID=2
INTERSECT
select cid from <<tablename>> where NetworkID=3
);
INTERSECT operator basically returns all the rows common in the queries. Thus, your data unpredicatbility can be handled in this way
Try xml path.
SELECT *
FROM Table_Name B
WHERE (SELECT [text()] = A.Network FROM Table_Name A WHERE A.CID = B.CID
ORDER BY CID, CAAccount FOR XML PATH('')) = 123
CTE Demo:
; WITH CTE(CAAccount, CID, Network) AS
(
SELECT 1 , 1, 1 UNION ALL
SELECT 2 , 1, 2 UNION ALL
SELECT 3 , 2, 1 UNION ALL
SELECT 4 , 2, 2 UNION ALL
SELECT 5 , 2, 3 UNION ALL
SELECT 6 , 3, 1 UNION ALL
SELECT 7 , 3, 2 UNION ALL
SELECT 8 , 3, 3 UNION ALL
SELECT 9 , 4, 1 UNION ALL
SELECT 10, 4, 2
) SELECT *
FROM CTE B
WHERE (SELECT [text()] = A.Network FROM CTE A WHERE A.CID = B.CID ORDER BY CID, CAAccount FOR XML PATH('')) = 123
Output:
CAAccount CID Network
3 2 1
4 2 2
5 2 3
6 3 1
7 3 2
8 3 3