I have a dataset like :
ID NAME
1 Aaron
2 Theon
3 Jon Snow
4 Jon Snow
4 Dany
5 Arya
5 Robert
5 Tyrion
I need to add a new column to this that shows the output based on the number of distinct names per ID. So expected output would be:
ID NAME Mapping
1 Aaron 1
2 Theon 1
3 Jon Snow 1
4 Jon Snow 2
4 Dany 2
5 Arya 3
5 Robert 3
5 Tyrion 3
I am confused about how to achieve this since I have tried a case statement where count(distinct(name)) does not return the right values.
You may try using COUNT as an analytic function:
SELECT
ID,
Name,
COUNT(*) OVER (PARTITION BY ID) Mapping
FROM yourTable
ORDER BY
ID;
Another approach to get COUNT of DISTINCT Name for each ID
SELECT *,
(SELECT Count(DISTINCT NAME)
FROM #table T
WHERE T1.id = T.id) Mapping
FROM #table T1
Online Demo
You can simply use below query
SELECT COUNT(DISTINCT NAME)
FROM YOUR_TABLE
GROUP BY ID
Thanks
Other method (specif SQL Server, otherwise use INNER JOIN LATERAL):
SELECT *
FROM #table f1
CROSS APPLY
(
select Count(*) Nb from #table f2
where f2.ID=f1.ID
) f3
Related
Lets say my table contains the following data
id
name
version
1
Rahul
1
1
Rahul
2
2
John
1
3
Mike
1
2
John
2
4
Rubel
1
5
David
1
1
Rahul
3
I need to filter the duplicate records with lower version. How can this be done?
The output essentially should be
id
name
version
1
Rahul
3
2
John
2
3
Mike
1
4
Rubel
1
5
David
1
For this dataset, aggregation seems sufficient:
select id, name, max(version) as max_version
from mytable
group by id, name
You can use not exists as follows:
select id, name, version
from your_table t
Where not exists
(Select 1 from your_table tt
Where tt.id = t.id and tt.version > t.version)
Or you can use analytical function row_number as follows:
Select id, name, version from
(select t.*,
Row_number() over (partition by id order by version desc) as rn
from your_table t) t
Where rn = 1
below is table:
Name | Hike% | Month
------------------------
A 7 1
A 6 2
A 8 3
b 4 1
b 7 2
b 7 3
Result should be:
Name | Hike% | Month
------------------------
A 8 3
b 7 2
Here is one way of doing this:
SELECT Name, [Hike%], Month
FROM
(
SELECT *, ROW_NUMBER() OVER (PARTITION BY Name ORDER BY [Hike%] DESC, Month) rn
FROM yourTable
) t
WHERE rn = 1
ORDER BY Name;
If you instead want to return multiple records per name, in the case where two or more records might be tied for having the greatest hike%, then replace ROW_NUMBER with RANK.
use correlated subquery
select Name,min(Hike) as Hike,min(Month) as Month
from
(
select * from tablename a
where Hike in (select max(Hike) from tablename b where a.name=b.name)
)A group by Name
You can use something similar to the below:
SELECT Name, MAX(Hike), Month
FROM table
GROUP BY Name, Month
Hope this helps :)
I have a table like
name num_try
John 2
John 1
Mike 3
Mike 2
Linda 2
And I want to know count distinct names group by MAX(num_try).
Desired result should look like
MAX(num_try) COUNT(DISTINCT(names))
2 2
3 1
Can you help me with this query?
select max_num_try, count(*) from
(
select name, max(num_try) as max_num_try
from table1
group by name
) a
group by max_num_try
order by max_num_try desc
The scenario I'm after for is :
Result = Nothing
CollectionOfTables = Tbl1, Tbl2, Tbl3
While(True){
CurrentTable = GetHighestPriorityTable(CollectionOfTables)
If(CurrentTable) = Nothing Then Break Loop;
RemoveCurrentTableFrom(CollectionOfTables)
ForEach ID in CurrentTable as TempRow {
If(Result.DoesntContainsId(ID)) Then Result.AddRow(TempRow)
}
}
Assume I have following three tables.
IdNameTable1, Priority 1
1 John
2 Mary
3 Elsa
IdNameTable2, Priority 2
2 Steve
3 Max
4 Peter
IdNameTable3, Priority 3
4 Frank
5 Harry
6 Mona
Here is the final result I need.
IdNameResult
1 John
2 Mary
3 Elsa
4 Peter
5 Harry
6 Mona
A few tips to keep in mind.
Number of actual tables is 10.
Number of rows per table exceeds 1 Million.
It's not necessary to use join in query, but because of amount of data I'm working with the query must be optimized and used set-operations in SQL not a Cursor script.
Here's a way to do it using UNION and ROW_NUMBER():
;With Cte As
(
Select Id, Name, 1 As Prio
From Table1
Union All
Select Id, Name, 2 As Prio
From Table2
Union All
Select Id, Name, 3 As Prio
From Table3
), Ranked As
(
Select Id, Name, Row_Number() Over (Partition By Id Order By Prio) As RN
From Cte
)
Select Id, Name
From Ranked
Where RN = 1
Order By Id Asc;
i got an "postgres" SQL problem.
I got a table which looks like this
id name level timestamp
1 pete 1 100
2 pete 1 200
3 pete 1 500
4 pete 5 900
7 pete 5 1000
9 pete 5 1200
15 pete 2 700
Now I want to delete the lines i dont need. i only want to now the first line where he get a new level and the last line he has this level.
id name level timestamp
1 pete 1 100
3 pete 1 500
15 pete 2 700
4 pete 5 900
9 pete 5 1200
(there much more columns like realmpoints and so on)
I have a solution if the the timestamp is only increasing.
SELECT id, name, level, timestamp
FROM player_testing
WHERE id IN ( SELECT MAX(dup.id)
FROM player_testing As dup
GROUP BY dup.name, dup.level)
UNION
SELECT MIN(dup.id)
FROM player_testing As dup
GROUP BY dup.name, dup.level)
)
ORDER BY ts
But I find no way to makes it work for my problem.
select id, name, level, timestamp
from (
select id,name,level,timestamp,
row_number() over (partition by name, level order by timestamp) as rn,
count(*) over (partition by name, level) as max_rn
from player_testing
) t
where rn = 1 or rn = max_rn;
Btw: timestamp is a horrible name for a column. For one reason because it's a reserved word, but more importantly because it doesn't document what the column contains. Is that a start_timestamp and end_timestamp a valid_until_timestamp, ...?
Here is an alternate solution to #a_horse_with_no_name's without over partition, and thus more generic SQL:
select *
from player_testing as A
where id = (
select min(id)
from player_testing as B
where A.name = B.name
and A.level = B.level
)
or id = (
select max(id)
from player_testing as B
where A.name = B.name
and A.level = B.level
)
Here is the fiddle to show it working: http://sqlfiddle.com/#!2/47bd44/1