The number of differences in a column

Question

I would like to retrieve a column of how many differences in letters in each row. For instance

If you have a a value \"test\" and another row has a value \"testing \", t

Answer 1

you can also use self joining query like below:

--create table tbl (id int,  value nvarchar(100), category int);
--insert into tbl values
--(1,N'test',1)
--,(2,N' testing',1)
--,(11,N'candy',2)      
--,(12,N'ca',2);
select A.*, LEN(B.value)-LEN(A.value) as difference
from tbl A LEFT JOIN tbl B on A.id +1 =B.id and A.category=B.category
--drop table tbl

Update: I noticed that you have oddly positioned the space at the end. SQL server most times does not count the trailing spaces when calculating length. So here's the hack on above query

select A.*, LEN(B.value+'>')-LEN(A.value+'>') as difference
from tbl A LEFT JOIN tbl B on A.id +1 =B.id and A.category=B.category

As pointed out in comments, that Id's may not be consecutive, in such cases try this :

create table #temp ( rownum int PRIMARY KEY IDENTITY(1,1), id int, value nvarchar(100), category int)
insert into #temp (id, value, category)
select id, value, category from tbl order by id asc


    select A.id, A.value, A.category, LEN(B.value+'>')-LEN(A.value+'>') as difference
    from #temp A LEFT JOIN #temp B on A.rownum +1 =B.rownum and A.category=B.category