My simple query returns data like this:
SELECT column1, column2 FROM table1
COLUMN1 COLUMN2
------- -------
CA A
CA B
CB C
CB D
I want to return column3 with these values (for same COLUMN1 value, I want to return same sequence number):
COLUMN3
-------
1
1
2
2
You can use analytic function DENSE_RANK.
SELECT column1,
column2,
DENSE_RANK() OVER(ORDER BY column1) as "column3"
FROM table1
See the following for some examples - oracle-base.com/articles/misc/rank-dense-rank-first-last-analytic-functions.php#dense_rank
Try this query,
Select column1, column2,
dense_rank() over (order by column1) as column3
from table1;
Related
My data is like below, it's in a single table
Column1 Column2
abc 100
abc 200
Now I need like below
abc 100 //here 200-100
I am banging my head on how to achieve this.
I have tried to use the row_number and then subtract using case statement like
Select
column1,
sum(
case when rownum=1
then column2
end
-
case when rownum=2
then column2
end
)
from table
group by column1
But this is giving me null.
Assuming there is no attribute which can define row ordering -
;with cte as(
select
row_number() over (order by (select null)) as IndexId,
Column1,
Column2
from #xyz
)
select sum(case when IndexID=1 then (-1 * Column2) else Column2 end), Column1
from cte
group by Column1
Input data-
declare #xyz table(Column1 varchar(10),Column2 int)
insert into #xyz
select 'abc' ,100 union all
select 'abc' ,200
Assuming you have an attribute rownum in table which is always 1 or 2 (it can be generated by some row_number() as you suggest in question, according to any order that is suitable for you)
Column1 Column2 Rownum
------------------------
abc 100 1
abc 200 2
then you can simply use
Select
column1,
sum(
case when rownum=1
then column2
else -column2
end
)
from table
group by column1
It performs a sum of the Column2 per Column1, however, in the row having rownum = 2 the Column2 value is negated. Therefore in our example you end up with 100 + (-200) = -100
You could do:
select column1, max(column2) - min(column2)
from t
group by column1;
Here is a short form of the answer above if you care:
SELECT
column1,
SUM(IIF(rownum=1,column2,-column2))
FROM table
GROUP BY column1
Goal is to find duplicates.
Select Column1, Column2, Column3
from Tablename
where Column1 = 1111 and Column2 = 2222
group by Column1, Column2, Column3
having count(*) > 1
This select query finds all the rows that are duplicates. I want to delete them all so I changed select to delete:
Delete from Tablename
where Column1 = 1111 and Column2 = 2222
group by Column1, Column2, Column3
having count(*) > 1
I get an error that says I can't use "group by".
What is another option to delete them all?
Try this query:
with v1 as
(select
ROW_NUMBER() OVER (ORDER BY Column1) AS ID,t1.*
FROM Tablename t1)
DELETE FROM v1 where Column1=1111 and Column2=2222
and id not in (select min(id) from v1 group by
Column1, Column2, Column3);
SQL Fiddle
I'm trying to isolate a problem with a violation of a unique key index. I'm pretty certain that the cause is resulting from columns that have the same value in 3 columns not having the same value in the 4th (when they should). As an example...
Key Column1 Column2 Column3 Column4
1 A B C D
2 A B C D
3 A B C D
4 A B C Z
I basically want to select column 4, or some way to let me identify column 4. I know it's a matter of using aggregrate functions but I'm not very familiar with them. Can anyone assist on a way to select Key, Column4 for rows that have a different column 4 value and the same column 1-3 values?
This is what you want:
select column1, column2, column3
from t
group by column1, column2, column3
having min(column4) <> max(column4)
Once you get the right values for the first three columns, you can join back in to get the specific rows.
Or, you can use window functions like this:
select t.*
from (select t.*, min(column4) over (partition by column1, column2 column3) as min4,
max(column4) over (partition by column1, column2 column3) as max4
from t
) t
where min4 <> max4;
If NULL is a valid "other" value that you want to count, you will need additional logic for that.
If you want to get all columns, then (it could be simpler if windowed count supported distinct but it's not):
with cte1 as (
select distinct * from Table1
), cte2 as (
select
*,
count(column4) over(partition by column1, column2, column3) as cnt
from cte1
)
select * from cte2 where cnt > 1;
if you want just to select key:
select
column1, column2, column3
from Table1
group by column1, column2, column3
having count(distinct column4) > 1
sql fiddle demo
I have an Oracle table that from which I need to select a given percentage of records for each type of a given set of unique column combination.
For example,
SELECT distinct column1, column2, Column3 from TableX;
provides me all the combination of unique records from that table. I need a % of each rows from each such combination. Currently I am using the following query to accomplish this, which is lengthy and slow.
SELECT *
FROM tableX Sample ( 3 )
WHERE Column1 = ‘value1’ and
Column2 = ‘value2’ and
Column3 = ‘value3
UNION
SELECT *
FROM tableX Sample ( 3 )
WHERE Column1 = ‘value1’ and
Column2 = ‘value2’ and
Column3 = ‘value4
UNION
…
…
SELECT *
FROM tableX Sample ( 3 )
WHERE Column1 = ‘valueP’ and
Column2 = ‘valueQ’ and
Column3 = ‘valueR’
Where the combination of suffix in the “Value” is unique for that table (obtained from the first query)
How can I improve the length of the query and speed?
Here is one approach:
select t.*
from (select t.*,
row_number() over (partition by column1, column2, column3 order by dbms_random()
) as seqnum,
count(*) over (partition by column1, column2, column3) as totcnt
from tablex t
) t
where seqnum / totcnt <= 0.10 -- or whatever your threshold is
It uses row_number() to assign a sequential number to rows in each group, in a random order. The where clause chooses the proportion that you want.
I have the following SQL
select count(*) col, column1, column2, column3 from TempTable
group by column1, column2, column3
order by 1 desc
so the column generated by the count will return a number and there are 17 rows that do not have the number 1 (duplicate rows as columns 1, 2 and 3 are primary keys) and i want to delete any that have the count greater than 1?
You can use the having-clause:
select count(*) col, column1, column2, column3
from TempTable group by column1, column2, column3
having count(*) > 1
order by 1 desc
To delete:
delete tt
from TempTable tt
inner join (select count(*) col, column1, column2, column3
from TempTable group by column1, column2, column3
having count(*) > 1) tmp
on tmp.column1 = tt.column1
and tmp.column2 = tt.column2
and tmp.column3 = tt.column3
First you insert the data in temporary table:
select count(*) col, column1, column2, column3
into #temp
from TempTable group by column1, column2, column3 order by 1 desc
Then, you delete the data, and insert it from the #temp table:
delete from TempTable
go
insert into TempTable select column1, column2, column3 from #temp
go