Say I have a table that looks like this:
Person Table
ID AccountID Name
1 6 Billy
2 6 Joe
3 6 Tom
4 8 Jamie
5 8 Jake
6 8 Sam
I have two queries that I know work by themselves:
Select Name Group1 from person where accountid = 6
Select Name Group2 from person where accountid = 8
But I want a single Result Set to look like this:
Group1 Group2
Billy Jamie
Joe Jake
Tom Same
You can use row_number() to assign a distinct value for each row, ans then use a FULL OUTER JOIN to join the two subqueries:
select t1.group1,
t2.group2
from
(
select name group1,
row_number() over(order by id) rn
from yourtable
where accountid = 6
) t1
full outer join
(
select name group2,
row_number() over(order by id) rn
from yourtable
where accountid = 8
) t2
on t1.rn = t2.rn;
See SQL Fiddle with Demo
I agree you should do this client side. But it can be done in T/SQL:
select G1.Name as Group1
, G2.Name as Group2
from (
select row_number() over (order by ID) as rn
, *
from Group
where AccountID = 6
) as G1
full outer join
(
select row_number() over (order by ID) as rn
, *
from Group
where AccountID = 8
) as G2
on G1.rn = G2.rn
order by
coalesce(G1.rn, G2.rn)
Related
I'm having trouble with selecting the highest aggregated group.
I have data in a table like this: Sales table:
ID
GroupDescription
Sales
1
Group1
2
1
Group1
15
1
Group2
3
1
Group3
2
1
Group3
2
1
Group3
2
2
Group1
2
2
Group2
5
2
Group3
3
2
Group4
12
2
Group4
2
2
Group4
2
I want to return 1 record for each ID. I also want to include the Group that had the most sales and the total sales for that group and ID.
Expected output:
ID
GroupDescription
SumSales
1
Group1
17
2
Group4
16
I have code working but I feel like it can be written much better:
SELECT * FROM
(
SELECT ROW_NUMBER() OVER(PARTITION BY ID ORDER BY ID, SumSales DESC) as RowNum, * FROM
(
SELECT
ID
,GroupDescription
,SUM(Sales) OVER(PARTITION BY ID,GroupDescription) as SumSales
FROM Sales
) t1
) t2
WHERE RowNum = 1
Aggregate by ID and GroupDescription and use window functions FIRST_VALUE() and MAX() to get the top group and its total:
SELECT DISTINCT ID,
FIRST_VALUE(GroupDescription) OVER (PARTITION BY ID ORDER BY SUM(Sales) DESC) GroupDescription,
MAX(SUM(Sales)) OVER (PARTITION BY ID) SumSales
FROM Sales
GROUP BY ID, GroupDescription;
See the demo.
Seems like you could use normal aggregation in the inner table. You can also put the row-number on the same level as that.
SELECT
s.ID
,s.GroupDescription
,s.SumSales
FROM
(
SELECT
s.ID
,s.GroupDescription
,SUM(s.Sales) as SumSales
,ROW_NUMBER() OVER (PARTITION BY s.ID ORDER BY SUM(s.Sales) DESC) as RowNum
FROM Sales s
GROUP BY
s.ID
,s.GroupDescription
) s
WHERE s.RowNum = 1;
db<>fiddle
Note that ordering a window function by the same column as the partitioning makes no sense, and will be ignored.
suppose I have the following table X:
Id Type Name
1 1 Jane
2 2 Mary
3 3 Rose
4 4 Rachel
5 4 Darren
6 4 Jay
What will be the select statement to generate:
Id Type Name
1 1 Jane
2 2 Mary
3 3 Rose
4 4 Rachel
that only the first row for each type will be selected? Appreciate a lot.
A simple method is to use a correlated subquery:
select t.*
from t
where t.id = (select min(t2.id) from t t2 where t2.type = t.type);
Here is the DEMO for the same.
Please try
SELECT t.* FROM test t
INNER JOIN (SELECT MIN(id) id FROM test GROUP BY TYPE) t2 ON t.id = t2.id;
You may use row_number() analytic function if your database supports it.
SELECT Id
,Type
,Name
FROM (
SELECT X.*
,row_number() OVER (
PARTITION BY type ORDER BY Id
) rn
FROM X
) a
WHERE rn = 1;
Demo
I need to make a query where only the last line of each user that has a car gets a license plate number.
ID UserId LicensePlate HasCar
1 1 ABC123 1
2 1 ABC123 1
3 2 NULL 0
4 3 UVW789 1
5 3 UVW789 1
Should become:
ID UserId LicensePlate HasCar
1 1 NULL 1
2 1 ABC123 1
3 2 NULL 0
4 3 NULL 1
5 3 UVW789 1
So I basically need to find all users with a licenseplate and change all but the last one and make the LicensePlate NULL
Assuming the ID column is an identity column so it can provide the ordering, something like this should do the trick:
;WITH CTE AS
(
SELECT Id,
UserId,
LicensePlate,
ROW_NUMBER() OVER(PARTITION BY UserId ORDER BY Id DESC) rn
FROM Table
WHERE HasCar = 1
)
UPDATE CTE
SET LicensePlate = NULL
WHERE rn > 1
You can try this
UPDATE l
SET l.LicensePlate = null
FROM Car l
INNER JOIN (SELECT UserId, Max(Id) AS max_id
FROM Car
GROUP BY UserId) m ON m.UserId = l.UserId
AND m.max_id <> l.id
You can do it with a join on the table itself like that :
UPDATE car c
INNER JOIN car c2 ON c.userId = c2.userId AND c.id < c2.id AND c.HasCar = 1 AND c2.HasCar = 1
SET c.LicensePlate = NULL
The condition c.id < c2.id will avoid to select the last line
By using LAG Function also you can achieve it.
;WITH License(ID,UserId,LicensePlate,HasCar)
as
(
SELECT 1,1,'ABC123',1 UNION ALL
SELECT 2,1,'ABC123',1 UNION ALL
SELECT 3,2,NULL ,0 UNION ALL
SELECT 4,3,'UVW789',1 UNION ALL
SELECT 5,3,'UVW789',1
)
SELECT ID,UserId,LAG(LicensePlate,1,NULL) OVER(PARTITION BY UserId ORDER BY LicensePlate),HasCar FROM License
If I have a table like this:
Id StateId Name
1 1 a
2 2 b
3 1 c
4 1 d
5 3 e
6 2 f
I want to select like below:
Id StateId Name
4 1 d
5 3 e
6 2 f
For example, Ids 1,3,4 have stateid 1. So select row with max Id, i.e, 4.
; WITH CTE AS
(
SELECT *, ROW_NUMBER() OVER(PARTITION BY STATEID ORDER BY ID DESC) AS RN
)SELECT ID, STATEID, NAME FROM CTE WHERE RN = 1
You can use ROW_NUMBER() + TOP 1 WITH TIES:
SELECT TOP 1 WITH TIES
Id,
StateId,
[Name]
FROM YourTable
ORDER BY ROW_NUMBER() OVER (PARTITION BY StateId ORDER BY Id DESC)
Output:
Id StateId Name
4 1 d
6 2 f
5 3 e
Disclaimer: I gave this answer before the OP had specified an actual database, and hence avoided using window functions. For a possibly more appropriate answer, see the reply by #Tanjim above.
Here is an option using joins which should work across most RDBMS.
SELECT t1.*
FROM yourTable t1
INNER JOIN
(
SELECT StateId, MAX(Id) AS Id
FROM yourTable
GROUP BY StateId
) t2
ON t1.StateId = t2.StateId AND
t1.Id = t2.Id
The following using a subquery, to find the maximum Id for each of the states. The WHERE clause then only includes rows with ids from that subquery.
SELECT
[Id], [StateID], [Name]
FROM
TABLENAME S1
WHERE
Id IN (SELECT MAX(Id) FROM TABLENAME S2 WHERE S2.StateID = S1.StateID)
I have a table_1:
id custno
1 1
2 2
3 3
and a table_2:
id custno qty descr
1 1 10 a
2 1 7 b
3 2 4 c
4 3 7 d
5 1 5 e
6 1 5 f
When I run this query to show the minimum order quantities from every customer:
SELECT DISTINCT table_1.custno,table_2.qty,table_2.descr
FROM table_1
LEFT OUTER JOIN table_2
ON table_1.custno = table_2.custno AND qty = (SELECT MIN(qty) FROM table_2
WHERE table_2.custno = table_1.custno )
Then I get this result:
custno qty descr
1 5 e
1 5 f
2 4 c
3 7 d
Customer 1 appears twice each time with the same minimum qty (& a different description) but I only want to see customer 1 appear once. I don't care if that is the record with 'e' as a description or 'f' as a description.
First of all... I'm not sure why you need to include table_1 in the queries to begin with:
select custno, min(qty) as min_qty
from table_2
group by custno;
But just in case there is other information that you need that wasn't included in the question:
select table_1.custno, ifnull(min(qty),0) as min_qty
from table_1
left outer join table_2
on table_1.custno = table_2.custno
group by table_1.custno;
"Generic" SQL way:
SELECT table_1.custno,table_2.qty,table_2.descr
FROM table_1, table_2
WHERE table_2.id = (SELECT TOP 1 id
FROM table_2
WHERE custno = table_1.custno
ORDER BY qty )
SQL 2008 way (probably faster):
SELECT custno, qty, descr
FROM
(SELECT
custno,
qty,
descr,
ROW_NUMBER() OVER (PARTITION BY custno ORDER BY qty) RowNum
FROM table_2
) A
WHERE RowNum = 1
If you use SQL-Server you could use ROW_NUMBER and a CTE:
WITH CTE AS
(
SELECT table_1.custno,table_2.qty,table_2.descr,
RN = ROW_NUMBER() OVER ( PARTITION BY table_1.custno
Order By table_2.qty ASC)
FROM table_1
LEFT OUTER JOIN table_2
ON table_1.custno = table_2.custno
)
SELECT custno, qty,descr
FROM CTE
WHERE RN = 1
Demolink