I want to select the rows between A and B from a table. The table has at least A rows but it might have less than B rows.
For example if A = 2, B = 5 and the table has 3 rows it should return rows 2 and 3.
How could I get the rows in such a range?
I am using Microsoft SQL Server 2008.
You can use something similar to what's being described in this SO question.
I.E.
SELECT * FROM (
SELECT *, ROW_NUMBER() OVER (ORDER BY YOUR_ORDERED_FIELD) as row FROM YOUR_TABLE
) a WHERE row > 5 and row <= 10
Where A = 5 and B = 10 in your example.
SELECT *,ROW_NUMBER() OVER
(ORDER BY ordercol) AS 'rank'
FROM table
where rank between #a and #b
Related
I'm using a query where a part of it gets the top 3 of a certain column.
It creates a distinct subquery of the column, limited by 3 number of rows, and then filters those rows to the main query to do the top 3.
WITH subquery AS (
SELECT col FROM (
SELECT DISTINCT col
FROM tbl
) WHERE ROWNUM <= 3
)
SELECT col
FROM tbl
WHERE tbl.col = subquery.col
So the original table is like this:
col
-----
a
a
a
b
b
b
c
d
d
e
f
f
f
f
And the query returns the top 3 of the column (not the top 3 rows which would only be a):
col
-----
a
a
a
b
b
b
c
I'm trying to learn if there is a more correct way of doing this as the real query is big and duplicating its size with a subquery that looks almost the same just to get the top 3 is hard to work with and understand/modify.
Is there a better way to do the top first 3 distinct values of one column in Oracle?
Yes, you can use dense_rank and avoid duplicated code:
select col
from (select col, dense_rank() over (order by col) rnk from tbl)
where rnk <= 3
demo
If we have a table with values for a and b, is there a way to only add up the b's if its not a duplicate a? For example
a b
1 2
2 3
2 3
so we would get only 5 (instead of 8)
A sort of
select sum(b if unique a),
from table
where ...
The following query selects the lowest value of b for each group a
select min(b) min_b
from mytable
group by a
You can then sum those values by selecting the sum from a derived table
select sum(min_b) from (
select min(b) min_b
from mytable
group by a
) t
http://sqlfiddle.com/#!9/d82c5/1
You haven't specified your RDBMS, but if you are using a database which supporting window functions like SQL Server, you can query the unique rows first by using WITH clause and ROW_NUMBER() function and then get the SUM out of that.
;WITH C AS(
SELECT a, b,
ROW_NUMBER() OVER (PARTITION BY a ORDER BY a) AS Rn
FROM Table1
)
SELECT SUM(b) FROM C
WHERE Rn = 1
SQL Fiddle
Let's suppose that I've got as a result from one query the next set of values of one column:
Value
1 A
2 B
3 C
4 D
5 E
6 F
7 G
8 H
9 I
10 J
Now, I would like to see this information with another order, establishing a limit to the number of values of every single subset. Now suppose that I choose 3 as a limit,the information will be given like this (one column for all the subsets):
Values
1 A, B, C
2 D, E, F
3 G, H, I
4 J,
Obviously, the last row will contain the remaining values when their number is smaller than the limit established.
Is it possible to perform a query like this in SQL?
What about if the limit is dynamic?. It can be chosen randomly.
create table dee_t (id int identity(1,1),name varchar(10))
insert into dee_t values ('A'),('B'),('c'),('D'),('E'),('F'),('g'),('H'),('I'),('J')
;with cte as
(
select (id-1)/3 +1 rno ,* from dee_t
) select rno ,
(select name+',' from cte where rno = c.rno for xml path('') )
from cte c group by rno
You can do this by using few calculations with row_number, like this:
select
GRP,
max(case when RN = 1 then Value end),
max(case when RN = 2 then Value end),
max(case when RN = 0 then Value end)
from (
select
row_number() over (order by Value) % 3 as RN,
(row_number() over (order by Value)+2) / 3 as GRP,
Value
from Table1
) X
group by GRP
The first row_number creates numbers for the columns (1,2,0,1,2,0...) and the second one creates numbers for the rows (1,1,1,2...). Those are then used to group the values into correct place using case, but you can also use pivot instead of it if you like it more.
If you want them into same column, of course just concatenate the cases instead of selecting them on different columns, but beware of nulls.
Example in SQL Fiddle
Thanks a lot for all your reply. Finally I've got a Solution with the help of Rajen Singh
This is the code than can be used:
WITH CTE_0 AS
(
SELECT DISTINCT column_A_VALUE AS id
FROM Table
WHERE column_A_VALUE IS NOT NULL
), CTE_1 AS
(
SELECT ROW_NUMBER() OVER (ORDER BY id) RN, id
FROM CTE_0
), CTE_2 AS
(
SELECT RN%30 GROUP, ID
FROM CTE_1
)SELECT STUFF(( SELECT ','''+CAST(ID AS NVARCHAR(20))+''''
FROM CTE_2
WHERE GROUP = A.GROUP
FOR XML PATH('')),1,1,'') IDS
FROM CTE_2 A
GROUP BY GROUP
I need a query with a column with row number (probably using ROW_NUMBER() ) and if the result are 8 rows (e.g.) the query should result 10 rows with rows 9 and 10 blank except row number. If the result is 15 rows the result should be 20 rows, and so on...
It is possivel?
Normally, something like this would be done in the application layer. However, you can do this in SQL:
select t.*
from table t
union all
select nulls.*
from (select 1 as n union all select 2 union all . . . select 10
) n cross join
(select count(*) cnt from table) cnt left join
table nulls
on 1 = 0
where 10 * floor(cnt / 10) + n.n <= cnt;
The first subquery gets all your data. The second gets the additional rows with NULL values. It uses a left join with "false" condition to get all the columns.
I want to get a subset of a table, here's the example:
1 A
2 A
3 B
4 B
5 C
6 D
7 D
8 D
I want to get the unique record, but with the smallest id:
1 A
3 B
5 C
6 D
How can I write the SQL in SQL Server? Thanks!
Use a common-table expression like this:
;WITH DataCTE AS
(
SELECT ID, OtherCol,
ROW_NUM() OVER(PARTITION BY OtherCol ORDER BY ID) 'RowNum'
FROM dbo.YourTable
)
SELECT *
FROM DataCTE
WHERE RowNum = 1
This "partitions" your data by the second column you have (A, B, C) and orders by the ID (1, 2, 3) - smallest ID first.
Therefore, for each "partition" (i.e. each value of your second column), the entry with RowNum = 1 is the one with the smallest ID for each value of the second column.
select min(id), othercol
from thetable
group by othercol
and maybe with
order by othercol
... at the end if thats important
Try this:
SELECT MIN(Id) AS Id, Name
FROM MyTable
GROUP BY Name
select min(id), column2
from table
group by column2
It helps if you provide the table information in the question - I've just guessed at the column names...