How to return a incremental group number per group in SQL

Question

I would like create a data query in SQL to incrementally number groups of rows, grouped on a common datetime and keep the "group numbers" incrementing on the next datetime and so on. These "group numbers" must not reset for each group as I have seen when using the partition by statement. Here is my sample data:

ts_DateTime          |ID   |Value|RowFilter|RequiredResult
--------------------------
2013/01/09 09:23:16  |8009 |0    |1        |1
2013/01/09 09:23:16  |8010 |0    |2        |1
2013/01/09 09:23:16  |8026 |0    |3        |1

2013/01/09 09:23:22  |8026 |0    |1        |2

2013/01/09 09:23:28  |8009 |0    |1        |3
2013/01/09 09:23:28  |8010 |0    |2        |3
2013/01/09 09:23:28  |8026 |0    |3        |3

2013/01/09 09:27:03  |8009 |0    |1        |4
2013/01/09 09:27:03  |8010 |0    |2        |4
2013/01/09 09:27:03  |8026 |0    |3        |4

2013/01/09 09:27:09  |8009 |0    |1        |5
2013/01/09 09:27:09  |8010 |0    |2        |5
2013/01/09 09:27:09  |8026 |0    |3        |5

2013/01/09 09:27:15  |8009 |0    |1        |6
2013/01/09 09:27:15  |8010 |0    |2        |6
2013/01/09 09:27:15  |8026 |0    |3        |6

The query I am using to get these results is :

select hl.ts_DateTime,  hl.Tagname as [ID],  hl.TagValue as [Value],
ROW_NUMBER() OVER (PARTITION BY hl.ts_datetime ORDER BY hl.tagname) AS RowFilter
from Table1 hl

So basically, looking at the RowFilter column, I am getting a unique ROW number per ts_DateTime partition. What I actually need is that for each ts_DateTime partition the RowFilter column should look like the Required result column.

Answer 1

you shouldn't be using ROW_NUMBER(),

• use DENSE_RANK() instead
• remove PARTITION BY

query,

SELECT hl.ts_DateTime,  
       hl.Tagname as [ID],  
       hl.TagValue as [Value],
       DENSE_RANK() OVER (ORDER BY ts_datetime) AS RowFilter
FROM   Table1 hl 
ORDER  BY RowFilter

• SQLFiddle Demo