SQL & PL/SQL

How do you detrmine which row to compare with.
Its clearly not the previous row judging by your example.

Here's a pointer. (Analytics )

with testdata as
(
select 'A' name, 1 num from dual union all
select 'B', 4 from dual union all
select 'C', 8 from dual union all
select 'D', 18  from dual union all
select 'h', 21 from dual union all
select 'E', 34  from dual union all
select 'f', 35 from dual union all
select 't', 36 from dual union all
select 'L', 51  from dual union all
select 'Z', 55 from dual 
)
select name,num
from
(
select name,num,lag(num,1,0) over (partition by 1 order by 1) prev_num from testdata
order by num
)
where num >= (prev_num+15)

To phrase it differently, don't you just want the lowest number in each "bucket" of 15?

select num
from (select trunc(num/15), min(num)
      from test
      group by trunc(num/15)
     )

How about this:

SQL> edit

Wrote file sqlplus_buffer.sql



  1  WITH test AS

  2  (

  3     SELECT 'A' AS name, 1 AS num FROM DUAL UNION ALL

  4     SELECT 'B' AS name, 4 AS num FROM DUAL UNION ALL

  5     SELECT 'C' AS name, 8 AS num FROM DUAL UNION ALL

  6     SELECT 'D' AS name, 18 AS num FROM DUAL UNION ALL

  7     SELECT 'h' AS name, 21 AS num FROM DUAL UNION ALL

  8     SELECT 'E' AS name, 34 AS num FROM DUAL UNION ALL

  9     SELECT 'f' AS name, 35 AS num FROM DUAL UNION ALL

 10     SELECT 't' AS name, 36 AS num FROM DUAL UNION ALL

 11     SELECT 'L' AS name, 51 AS num FROM DUAL UNION ALL

 12     SELECT 'Z' AS name, 55 AS num FROM DUAL

 13  )

 14  SELECT a.name,a.num,a.diff

 15  FROM

 16  (SELECT name,num,num-(LAG(num,1) OVER (order by num)) AS diff FROM test order by num) a

 17* WHERE a.diff >= 15 OR a.diff IS NULL

SQL> /



N        NUM       DIFF

- ---------- ----------

A          1

L         51         15



SQL>

I hope this helps. I had a hard time understanding your requirements.

Thanks, but the solution is not correct.
Sorry, but the problem is very difficult to explain.

the range(15) start from the first record, so if the first number is 14, the second number will be >= 30.
Other example:

A, 14
B, 15
C, 19
D, 29
E, 30
F, 50
G, 51

I want select only 3 records: (A,14) , (E, 30) , (F, 50)

I hope that this example is more clearly.

Ah I got you now

Always choose first number
Second number is first number that is 15 greater than first number
3rd number is first number that is 15 greater than second number.
etc

which gives
A, 14
E, 30
F, 50

I solved same question :-)
673100

and my site mentions same question B-)
http://www.geocities.jp/oraclesqlpuzzle/10-245.html

thanks, very good, very well ...

I have an other question ....
I have the same scenario but more complicated, I have 3 columns: surname, name, datatime
and I have to use the same reasoning but for each surname:
example:
the range is 15 minuts

surname, name, datatime (dd/mm/yyyy hh24.mi)
x, a, 03/09/2008 10.00
x, b, 03/09/2008 10.08
x, c, 03/09/2008 10.16
y, a, 03/09/2008 10.10
y, b, 03/09/2008 10.30
y, c, 03/09/2008 10.50

i want select 5 record:
(x, a, 03/09/2008 10.00), (x, c, 03/09/2008 10.16) , (y, a, 03/09/2008 10.10) , (y, b, 03/09/2008 10.30) ,
(y, c, 03/09/2008 10.50)

thanks

I don't think that is the correct answer. I think that will only work if you always manage to stay at the bottom boundary of your window (e.g. 14, 29, 44, 59 etc.)

It fails with the following data (gives you 40 and 45).

Aketi Jyuuzu's method works. Method is to work out what the next row would be if any given row is chosen (i.e. the first row that is at least 15 away), and then use a hierarchical query to choose the rows you would actually need starting with whatever is your first row.

(actually need to create a table so you can use rowids)

create table testxx as (
select 'A' nam, 14 num from dual union all
select 'B', 15 from dual union all
select 'C', 19 from dual union all
select 'D', 40 from dual union all
select 'E', 41 from dual union all
select 'F', 45 from dual union all
select 'G', 56 from dual);


with WorkView as (
Select nam,num,RowID as Row_ID,min(num) over() as startnum,
first_value(RowID) over(order by num
range between 15 following
and unbounded following) as childRowID
from Testxx)
select nam,num
from WorkView
Start With num = startnum
connect by prior childRowID = Row_ID;