SQL Server developers and database architects often find they have a need to sequence query results or generate a cumulative sum for a group of rows in a table. SQL Server does not have a Pseudo row-id similar to other RDBMS.

In this article, I am going to guide the developers and database architects to use co-related sub-queries and/or identity functions to generate such sequential numbers and cumulative summations in query results.

Example 1:

Generate sequential number for a table, which has at least one unique numeric column.

Let us consider we have a table as shown below.

Use tempdb
go
Create table Mytable1 (au_id int, authors_name varchar(100))
Go
insert into MyTable1 select 100,'Mathew Arnold'
insert into MyTable1 select 140,'Keith Davis'
insert into MyTable1 select 76,'David Taylor'
insert into MyTable1 select 127,'Agatha Christy'
insert into MyTable1 select 12,'Sidney Sheldon'
go

Query

select au_id,authors_name from Mytable1 order by au_id

Results

au_id is unique in this table, so it is easy to use a co-related sub-query to generate sequential numbers.

Query

SELECT (SELECT count(au_id) FROM Mytable1 AS x WHERE x.au_id<= y.au_id) AS
Sequence, au_id,authors_name
FROM Mytable1 AS y order by au_id

Results

Note: "au_id" is a unique column.

Example 2:

Generate unique sequence numbers for a table that has no unique column.

Let us consider the table shown below. For tables with no unique columns, it is easy to use the identity function to generate unique sequence numbers.

Use tempdb
go
Create table Mytable2 (au_id int, authors_name varchar(100))
Go
insert into MyTable2 select 100,'Mathew Arnold'
insert into MyTable2 select 140,'Keith Davis'
insert into MyTable2 select 76,'David Taylor'
insert into MyTable2 select 127,'Agatha Christy'
insert into MyTable2 select 12,'Sidney Sheldon'
insert into MyTable2 select 12,'Mcarthur'
insert into MyTable2 select 76,'Alan Smiles'
insert into MyTable2 select 100,'Kreisler'
go

Query

select * from mytable2 order by au_id

Results

Query

select identity(int,1,1) as Sequence, au_id,authors_name into #x from Mytable2 order by au_id
go
select * from #x
go
drop table #x
go

Results