I am looking to join 2 tables with top n results of other table as explained below.
OrderHeader
OH_Id OrderDate
----------------------
1 2014-06-01
2 2014-06-02
3 2014-06-03
4 2014-06-04
5 2014-06-05
OrderProducts
OP_Id OH_Id Quantity
------------------------------
1 1 1
2 1 2
3 2 1
4 3 3
5 4 4
6 4 1
7 4 2
8 5 2
9 5 1
I am expecting result something like this for top 3 orders (4 rows).
OH_Id OrderDate Op_Id Quantity
------------------------------------------------
1 2014-06-01 1 1
1 2014-06-01 2 2
2 2014-06-02 3 1
3 2014-06-03 4 3
Note: I am looking specifically to join 2 tables rather writing as SP or looped queries.
select top 3 o.oh_id, o.orderdate, oo.op_id, oo.quantity
from orderheader o
join orderproducts oo on o.oh_id = oo.oh_id
If you want the first 3 order numbers from OrderHeader with all corresponding rows from OrderProducts try this.
select o.oh_id
,o.orderdate
,oo.op_id
,oo.quantity
from (SELECT TOP 3 *
FROM orderheader
ORDER BY OH_ID --or Date etc...
) o
INNER JOIN orderproducts oo
on o.oh_id = oo.oh_id
I think your description is confusing. You don't want top 3 as that will return only 3 rows. You just want ids 1-3 from what it sounds like.
SELECT *
FROM OrderHeader a
JOIN OrderHeader b on a.oh_id = b.oh_id
WHERE a.oh_id <= 3
you have to use a sub query like this
SELECT * FROM OrderHeader
INNER JOIN OrderProducts ON OrderHeader.OH_Id = OrderProducts.OH_Id
WHERE OrderHeader.OH_Id IN (SELECT TOP 3 OH_Id FROM OrderHeader)
A test sql fiddle is here
hope this helps
Related
I am still learning many new things about SQL such as PARTITION BY and CTEs. I am currently working on a query which I have cobbled together from a similar question I found online. However, I can not seem to get it to work as intended.
The problem is as follows -- I have been tasked to show rank promotions in an organization from the begining of 2022 to today. I am working with 2 primary tables, an EMPLOYEES table and a PERIODS table. This periods table captures a snapshot of any given employee each month - including their rank at the time. Each of these months is also assigned a PeriodID (e.g. Jan 2022 = PeriodID 131). Our EMPLOYEE table holds the employees current rank. These ranks are stored as an int (e.g. 1,2,3 with 1 being lowest rank). It is possible for an employee to rank up more than once in any given month.
I have simplified the used query as much as I can for the sake of this problem. Query follows as:
;WITH x AS
(
SELECT
e.EmployeeID, p.PeriodID, p.RankID,
rn = ROW_NUMBER() OVER (PARTITION BY e.EmployeeID ORDER BY p.PeriodID DESC)
FROM employees e
LEFT JOIN periods p on p.EmployeeID= e.EmployeeID
WHERE p.PeriodID <= 131 AND p.PeriodID >=118 --This is the time range mentioned above
),
rest AS (SELECT * FROM x WHERE rn > 1)
SELECT
main.EmployeeID,
PeriodID = MIN(
CASE
WHEN main.CurrentRankID = Rest.RankID
THEN rest.PeriodID ELSE main.PeriodID
END),
main.RankID, rest.RankID
FROM x AS main LEFT OUTER JOIN rest ON main.EmployeeID = rest.EmployeeID
AND rest.rn >1
LEFT JOIN periods p on p.EmployeeID = e.EmployeeID
WHERE main.rn = 1
AND NOT EXISTS
(
SELECT 1 FROM rest AS rest2
WHERE EmployeeID = rest.EmployeeID
AND rn < rest.rn
AND main.RankID <> rest.RankID
)
and p.PeriodID <= 131 AND p.PeriodID >=118
GROUP BY main.EmployeeID, main.PeriodID, main.RankID, rest.RankID
As mentioned before, this query was borrowed from a similar question and modified for my own use. I imagine the bones of the query is good and maybe I have messed up a variable somewhere but I can not seem to locate the problem line. The end goal is for the query to result in a table showing the EmployeeID, PeriodID, the rank they are being promoted from, and the rank they are being promoted to in the month the promotion was earned. Similar to the below.
EmployeeID
PeriodID
PerviousRankID
NewRank
123
131
1
2
123
133
2
3
Instead, my query is spitting out repeating previous/current ranks and the PeriodIDs seem to be static (such as what is shown below).
EmployeeID
PeriodID
PerviousRankID
NewRank
123
131
1
1
123
131
1
1
I am hoping someone with a greater knowledge base on these functions is able to quickly notice my mistake.
If we assume some example DML/DDL (it's really helpful to provide this with your question):
DECLARE #Employees TABLE (EmployeeID INT IDENTITY, Name VARCHAR(20), RankID INT);
DECLARE #Periods TABLE (PeriodID INT, EmployeeID INT, RankID INT);
INSERT INTO #Employees (Name, RankID) VALUES ('Jonathan', 10),('Christopher', 10),('James', 10),('Jean-Luc', 8);
INSERT INTO #Periods (PeriodID, EmployeeID, RankID) VALUES
(1,1,1),(2,1,1),(3,1,1),(4,1,8 ),(5,1,10),(6,1,10),
(1,2,1),(2,2,1),(3,2,1),(4,2,8 ),(5,2,8 ),(6,2,10),
(1,3,1),(2,3,1),(3,3,7),(4,3,10),(5,3,10),(6,3,10),
(1,4,1),(2,4,1),(3,4,1),(4,4,8 ),(5,4,9 ),(6,4,9 )
Then we can accomplish what I think you're looking for using a OUTER APPLY then aggregates the values based on the current-row values:
SELECT e.EmployeeID, e.Name, e.RankID AS CurrentRank, ap.PeriodID AS ThisPeriod, p.PeriodID AS LastRankChangePeriodID, p.RankID AS LastRankChangedFrom, ap.RankID - p.RankID AS LastRankChanged
FROM #Employees e
LEFT OUTER JOIN #Periods ap
ON e.EmployeeID = ap.EmployeeID
OUTER APPLY (
SELECT EmployeeID, MAX(PeriodID) AS PeriodID
FROM #Periods
WHERE EmployeeID = e.EmployeeID
AND RankID <> ap.RankID
AND PeriodID < ap.PeriodID
GROUP BY EmployeeID
) a
LEFT OUTER JOIN #Periods p
ON a.EmployeeID = p.EmployeeID
AND a.PeriodID = p.PeriodID
ORDER BY e.EmployeeID, ap.PeriodID DESC
Using the correlated subquery we get a view of the data which we can filter using the current-row values, and we aggregate that to return the period we're looking for (where it's before this period, and it's not the same rank). Then it's just a join back to the Periods table to get the values.
You used an LEFT JOIN, so I've preserved that using an OUTER APPLY. If you wanted to filter using it, it would be a CROSS APPLY instead.
EmployeeID
Name
CurrentRank
ThisPeriod
LastRankChangePeriodID
LastRankChangedFrom
LastRankChanged
1
Jonathan
10
6
4
8
2
1
Jonathan
10
5
4
8
2
1
Jonathan
10
4
3
1
7
1
Jonathan
10
3
1
Jonathan
10
2
1
Jonathan
10
1
2
Christopher
10
6
5
8
2
2
Christopher
10
5
3
1
7
2
Christopher
10
4
3
1
7
2
Christopher
10
3
2
Christopher
10
2
2
Christopher
10
1
3
James
10
6
3
7
3
3
James
10
5
3
7
3
3
James
10
4
3
7
3
3
James
10
3
2
1
6
3
James
10
2
3
James
10
1
4
Jean-Luc
8
6
5
9
-1
4
Jean-Luc
8
5
4
8
1
4
Jean-Luc
8
4
3
1
7
4
Jean-Luc
8
3
4
Jean-Luc
8
2
4
Jean-Luc
8
1
Now we can see what the previous change looked like for each period. Currently Jonathan is has RankID 10. Last time that was different was in PeriodID 4 when it was 8. The same was true for PeriodID 5. In PeriodID 4 he had RankID 8, and prior to that he had RankID 1. Before that his Rank hadn't changed.
Jean-Luc was actually demoted as his last change. I don't know if this is possible within your model.
I have two tables in SQLITE one table FastData records data at a high rate while the other table SlowData records data at a lower rate. FastData and SlowData share a primary key (PK) that represents time of data capture. As such the two tables could look like:
Fast Data Slow Data
Pk Value1 Pk Value2
2 1 1 1
3 2 4 2
5 3 7 3
6 4
7 5
9 6
I would like to create a Select statement that joins these two tables filling in the SlowData with the previous captured data.
Join Data
Pk Value1 Value2
2 1 1
3 2 1
5 3 2
6 4 2
7 5 3
9 6 3
You may try the following approach which uses row_number to determine the most recent entry as it relates to Pk as the ideal entry for Value2 after performing a left join.
SELECT
Pk,
Value1,
Value2
FROM (
SELECT
f.Pk,
f.Value1,
s.Value2,
ROW_NUMBER() OVER (
PARTITION BY f.Pk, f.Value1
ORDER BY s.Pk DESC
) rn
FROM
fast_data f
LEFT JOIN
slow_data s ON f.Pk >= s.Pk
) t
WHERE rn=1;
Pk
Value1
Value2
2
1
1
3
2
1
5
3
2
6
4
2
7
5
3
9
6
3
View working demo on DB Fiddle
You need a LEFT join of the tables and FIRST_VALUE() window function to pick Value2:
SELECT DISTINCT f.Pk, f.Value1,
FIRST_VALUE(s.Value2) OVER (PARTITION BY f.Pk ORDER BY s.Pk DESC) Value2
FROM FastData f LEFT JOIN SlowData s
ON s.Pk <= f.Pk;
See the demo.
I keep product categories with parentid logic. I need to get all products under a category, but from top to down hierarchy. For example I have these tables:
ProductCategories
id CategoryID ProductID
1 4 1
2 5 2
3 6 3
4 8 4
5 8 5
6 9 5
7 9 2
Categories
ID CategoryName ParentID
1 Kids NULL
2 Accesories 1
3 Shoes 2
4 Flat Shoes 3
5 Leather Sandals 4
6 Sneakers 3
7 Clothing 1
8 T-Shirts 7
9 Bestsellers 1
Products
ID ProductName
1 White Espadrilles
2 Tan Leather Sandals
3 Beige Sneakers
4 Linen T-Shirt
5 Cotton T-Shirt
I use below Sql recursive query:
with CTE as
(
select c.ID,c.ParentID,c.CategoryName,p.ProductName
from Categories c
join ProductCategories pc
on pc.CategoryID=c.ID
join Products p
on pc.ProductID=p.ID
where c.ID = 5 --start id
union all
select ce.ID,ce.ParentID,ce.CategoryName,p.ProductName
from Categories ce
join ProductCategories pc
on pc.CategoryID=ce.ID
join Products p
on pc.ProductID=p.ID
join CTE
on ce.ID=CTE.ParentID
)
select * from CTE
Above query returns below result for a given CategoryID = 5 :
ID ParentID CategoryName ProductName
5 4 Leather Sandals Tan Leather Sandals
4 3 Flat Shoes White Espadrilles
if categoryID = 1 or 2 no record comes.
I dont have a product directly for Accesories category, but I have for it's child categories, so I should get all products under that, from top to down.
How can I do this?
You don't say which database you are using so I will give you a generic solution.
You can use a recursive CTE to produce a list of categories that include the starting one, plus all its children (in multiple levels). Then simple joins will do the rest, as you have already tried.
Here's an example. Tweak as necessary for your specific database:
with
categories_subtree as (
select id, categoryname, parentid
from categories
where id = 5 -- starting category
union all
select c.id, c.categoryname, c.parentid
from categories_subtree s
join categories c on c.parentid = s.id
)
select
p.id,
c.parentid
c.categoryname,
p.productname
from categories_subtree c
join productcategories pc on pc.categoryid = c.id
join products p on p.id = pc.productid
I have following table with hierarchical data:
FolderId ParentFolderId NumberOfAffectedItems
---------------------------------------------
1 NULL 2
2 1 3
3 2 5
4 2 3
5 1 0
I want to find number of affected items under each folders and all of its children. I can write a recursive cte, which can produce following result, after that by doing group by I can find out what I want.
Normal recursive CTE:
WITH FolderTree AS
(
SELECT
fsa.FolderId AS ParentFolderId,
fsa.FolderId AS ChildFolderId,
fsa.NumberOfReportsAffected
FROM
FoldersWithNumberOfReportsAffected fsa
UNION ALL
SELECT
ft.ParentFolderId,
fsa.FolderId AS ChildFolderId,
fsa.NumberOfReportsAffected
FROM
FoldersWithNumberOfReportsAffected fsa
INNER JOIN
FolderTree ft ON fsa.ParentFolderId = ft.ChildFolderId
)
Result:
ParentFolderId ChildFolderId NumberOfAffectedItems
--------------------------------------------------
1 1 2
1 2 3
1 3 5
1 4 3
1 5 0
2 2 3
2 3 5
2 4 3
3 3 5
4 4 3
5 5 0
But I want to optimize it, I want to start from the leaf child, while
moving through the CTE itself, I want to compute NumberOfAffectedItems.
Expected CTE
WITH FolderTree AS
(
SELECT
fsa.FolderId AS LeafChildId,
fsa.FolderId AS ParentFolderId,
fsa.NumberOfReportsAffected
FROM
FoldersWithNumberOfReportsAffected fsa
LEFT JOIN
FoldersWithNumberOfReportsAffected f ON fsa.folderid = f.ParentfolderId
WHERE
f.ParentfolderId is null -- this is finding leaf child
UNION ALL
SELECT
ft.LeafChildId,
fsa.FolderId AS ParentFolderId,
fsa.NumberOfReportsAffected + ft.NumberOfReportsAffected AS [ComputedResult]
FROM
FoldersWithNumberOfReportsAffected fsa
INNER JOIN
FolderTree ft ON fsa.FolderId = ft.ParentFolderId
)
Result:
LeafChildId ParentFolderId ComputedNumberOfAffectedItems
---------------------------------------------------------
3 3 5
3 2 8
3 1 10
4 4 3
4 2 5
4 1 7
5 5 0
5 1 2
If I group by ParentFolderId, I will get a wrong result, the reason is while doing computing in CTE, the same parent folder is visited from multiple
children, hence results in a wrong result. I want to find out is there anyway we can compute the result while going through the CTE itself.
Please check the following solution. I used your cte as basis and added the calculation (as column x) to it:
DECLARE #t TABLE(
FolderID INT
,ParentFolderID INT
,NumberOfAffectedItems INT
);
INSERT INTO #t VALUES (1 ,NULL ,2)
,(2 ,1 ,3)
,(3 ,2 ,5)
,(4 ,2 ,3)
,(5 ,1 ,0);
WITH FolderTree AS
(
SELECT 1lvl,
fsa.FolderId AS LeafChildId,
fsa.ParentFolderId AS ParentFolderId,
fsa.NumberOfAffectedItems
FROM
#t fsa
LEFT JOIN
#t f ON fsa.folderid = f.ParentfolderId
WHERE
f.ParentfolderId is null -- this is finding leaf child
UNION ALL
SELECT lvl + 1,
ft.LeafChildId,
fsa.ParentFolderId,
fsa.NumberOfAffectedItems
FROM
FolderTree ft
INNER JOIN #t fsa
ON fsa.FolderId = ft.ParentFolderId
)
SELECT LeafChildId,
ISNULL(ParentFolderId, LeafChildId) ParentFolderId,
NumberOfAffectedItems,
SUM(NumberOfAffectedItems) OVER (PARTITION BY LeafChildId ORDER BY ISNULL(ParentFolderId, LeafChildId) DESC) AS x
FROM FolderTree
ORDER BY 1, 2 DESC
OPTION (MAXRECURSION 0)
Result:
LeafChildId ParentFolderId NumberOfAffectedItems x
3 3 2 2
3 2 5 7
3 1 3 10
4 4 2 2
4 2 3 5
4 1 3 8
5 5 2 2
5 1 0 2
I am new to the recursive CTE concept and a problem at hand, I got a tiny feeling that the problem can be solved by using recursive CTE. Let me know what you guys think.
Two tables:
Table one is a self referencing Location table with ID, ParentID, Level and Description.
Table two is an asset table which records individual assets and has a foreign key to Location table ID field.
Table1:
ID Description ParentID Level
1 Site1 NULL 1
2 Site2 NULL 1
3 Building1 1 2
4 Building2 1 2
5 Floor1 3 3
6 Floor2 3 3
7 Floor3 4 3
8 Place1 5 4
9 Place2 7 4
Table2:
ID Description Quantity LocationID
1 Desk 3 8
2 Lamp 1 8
3 PC 10 9
I would like to create a stored procedure with a input parameter of #Level and returns all the Location records at that level and the number of assets within the location (including sub levels).
For example, if #Level = 3, the stored procedure should return:
ID Description AssetCount
5 Floor1 4
6 Floor2 0
7 Floor3 10
If #Level = 2, the stored procedure should return:
ID Description AssetCount
3 Building1 4
4 Building2 10
If the problem is not clear, please let me know.
Well, nothing special here, just a recursive CTE joined with the other table, and the results are what you expected:
declare #level int = 3
;with CTE as (
select id as origid, id, Description, parentid
from table1 where level = #level
union all
select CTE.origid, t1.id, CTE.Description, t1.parentid
from CTE join table1 t1 on
CTE.id = t1.parentid
)
select origid, CTE.description, isnull(sum(t2.Quantity),0) as Quantity
from CTE left outer join table2 t2 on CTE.id = t2.locationid
group by origid, CTE.description
SQL Fiddle