Question

I have a piece of script using cursor to sequence rows in a table. For example, the table looks like this,
SSN, Kid_SSN, Kid_DOB, Seq# to list every person with 1 or more kids. I want to update Seq# to label each kid as 1,2,3… based on Date Of Birth.
I used cursor for update to get it done successfully in SQL server 2008. My current trouble is that this same script wouldn’t run as expected in sql server 2012. The problem is in SQL 2012 cursor fetch NEXT more than 1 row at a time. So question is where can I set the cursor fetch size? I searched around but came up no good answer.
Anyone here can shed some light? thanks.

Scrip looks like this:

DECLARE @SocialSecurity varchar(9), @PersonID int, @Dep_SSN varchar(9)
DECLARE @LastName varchar(20), @FirstName varchar(20), @BirthDate datetime, 
    @Number int

DECLARE @ssn varchar(9) = '000000000'
DECLARE @Mem int = 1
DECLARE cur cursor
FOR SELECT * FROM kids
FOR UPDATE OF Number;

OPEN cur;

FETCH NEXT FROM cur INTO @SocialSecurity, @PersonID, @Dep_SSN, @LastName, @FirstName, 
    @BirthDate, @Number;

WHILE @@FETCH_STATUS = 0
BEGIN

IF @SocialSecurity = @ssn
BEGIN

UPDATE kids
SET Number = @Mem+1
WHERE CURRENT OF cur
SET @Mem = @Mem+1
END;
ELSE
BEGIN
SET @ssn = @SocialSecurity
SET @Mem = 1
END;
FETCH NEXT FROM cur INTO @SocialSecurity, @PersonID, @Dep_SSN, @LastName, @FirstName, 
    @BirthDate, @Number;
END;
CLOSE cur;
DEALLOCATE cur;

More info on this problem.
kids is a temp table generated by ‘SELECT .. INTO’ and a simplified set looks like this

SSN       Kid_SSN        DOB        Seq#
123123123 987987987      1/1/2000   1
123123123 987987988      1/1/2003   1
123123125 890890890      2/3/2002   1

So all seq# are initiated to 1. After going through the script above, I expect table kids to
look like this

SSN       Kid_SSN        DOB        Seq#
123123123 987987987      1/1/2000   1
123123123 987987988      1/1/2003   2
123123125 890890890      2/3/2002   1

The script ran perfectly to achieve this on server 2008 R2, but not on server 2012. Furthermore, I found that it only updated row 88, 176 and so on, if applicable. That is why I think cursor fetch 88 rows at a time. But on server 2008 it apparently fetch 1 row at a time as I expected. Hope this will explain the problem I have.
I want to force cursor fetching 1 row at a time to make it work on server 2012, though it’s not efficient. Or, how to do sequencing without using cursor? Thanks.

Answer 1

Would it work to replace the entire script with a rank over function?

Something like

select *, rank() over (partition by SSN, Kid_DOB order by Kid_SSN) as SeqNum
from kids

I think this should work and if not you can tweak the partition and order by to make it work.