Alternative to SQL window functions in Sybase - sybase

Question

I am working on Sybase Adaptive Server Enterprise (version 12.5.0.3). Trying to use Row_number() OVER (Partition by columnname order by columnname). When I execute the query it is throwing an exception saying that the syntax near OVER is incorrect. I have searched for proper row_number() syntax for sybase database, but there is nothing wrong in the syntax. I guess that the Sybase version that am using does not support row_number() OVER. I even tried dense_rank() OVER, but am getting the same error.
I need to know whether it is really a syntax issue or its because of Sybase's low version which is not supporting the key words?
If the issue is with the version, then is there any alternative for row_number OVER and dense_rank() OVER for sybase database.
My Query:
select cr.firstname, cr.lastname, cr.dob,cr.phone,
row_number() over (patition by cr.dob order by createddate) "rank"
from ff.CrossReferenceTable cr
Error Message:
Server Message: Number 156, Severity 15
Server 'MyServer', Line 1:
Incorrect syntax near the keyword 'over'.

Answer 1

Right, unfortunately Sybase ASE doesn't support row_number() function as well as rank() and dense_rank().
However, in some simple cases, where partition clause is not used it could be converted in the way like
select rank=identity(music), * into #new_temp_tab1 from CrossReferenceTable order by createddate
select firstname, lastname, dob, phone, rank from #new_temp_tab1
In your case it's going to be a little bit more complicated, I can recommend using cursor with temporary table to emulate row_number() over partition by behavior.
Please have a look at the example below:
create table CrossReferenceTable
(
firstname varchar(50),
lastname varchar(50),
dob int,
phone char(10),
createddate date
)
go
create proc sp_CrossReferenceTable
as
begin
declare #i int
declare #cur_firstname varchar(50)
declare #cur_lastname varchar(50)
declare #cur_dob int
declare #cur_phone varchar(10)
declare #cur_rank int
declare cur cursor for
select
cr.firstname,
cr.lastname,
cr.dob,
cr.phone,
count(*) AS "rank"
from
CrossReferenceTable cr
group by
cr.dob
order by
cr.dob,
createddate
CREATE TABLE #CrossReferenceTable_TEMP
(
firstname varchar(50),
lastname varchar(50),
dob int,
phone char(10),
rank INT
)
open cur
fetch cur into
#cur_firstname,
#cur_lastname,
#cur_dob,
#cur_phone,
#cur_rank
set #i = #cur_rank
while ##SQLSTATUS = 0
begin
if #i = 0
set #i = #cur_rank
insert into #CrossReferenceTable_TEMP
select
#cur_firstname,
#cur_lastname,
#cur_dob,
#cur_phone,
case
when #cur_rank > 1 then #cur_rank - (#i - 1)
ELSE #cur_rank
end as "rank"
set #i = #i - 1
fetch cur into
#cur_firstname,
#cur_lastname,
#cur_dob,
#cur_phone,
#cur_rank
end
select
firstname,
lastname,
dob,
phone,
rank
from
#CrossReferenceTable_TEMP
end
go
exec sp_CrossReferenceTable

Answer 2

Try the generic query below to have same effect as ROW_NUMBER()
SELECT
A.MyPartitionColumn,
A.MyRunningNumberColumn,
( SELECT count(*)
FROM MyTable
WHERE MyPartitionColumn = A.MyPartitionColumn
AND MyRunningNumberColumn <= A.MyRunningNumberColumn
) AS "Row_Number"
FROM MyTable A
ORDER BY MyPartitionColumn, MyRunningNumberColumn