Question

I have got an over 500 rows table with a column called ID which is of datetype INT. Currently the values are all NULL.

What I want to achieve is to populate the ID column with an incremental number for each row, say 1, 2, 3, 4, …, 500 etc.

Please give me a help with any idea how to achieve this by SQL script.

Answer 1

using ROW_NUMBER in a CTE is one way, but here’s an alternative; Create a new id1 column as int identity(1,1), then copy over to id, then drop id1:

-- sample table
create table myTable(id int, value varchar(100));

-- populate 10 rows with just the value column
insert into myTable(value)
select top 10 'some data'
from sys.messages;
go

-- now populate id with sequential integers
alter table myTable add id1 int identity(1,1)
go
update myTable set id=id1;
go
alter table myTable drop column id1;
go
select * from myTable

Result:

id          value
----------- -------------
1           some data
2           some data
3           some data
4           some data
5           some data
6           some data
7           some data
8           some data
9           some data
10          some data

While you could also drop and recreate ID as an identity, it would lose its ordinal position, hence the temporary id1 column.