Question

I have table tb1(col1, col2), col2 is varchar(50). For instance,

col1    col2
item1   abc
item2   a
item3   ed

I want to write a stored procedure to parse col2 and create a temp table like following:

col1    col2
item1   a
item1   b
item1   c
item2   a
item3   e
item3   d

Can anybody help me out here?

Answer 1

If you know the maximum length of the string, the easiest way is doing a simple union:

select col1, substring(col2, 1, 1) as col2
from t
where len(col2) >= 1 union all
select col1, substring(col2, 2, 1) as col2
from t
where len(col2) >= 2 union all
select col1, substring(col2, 3, 1) as col2
from t
where len(col2) >= 3 union all

If the length is never too long, you can do something like this to simplify the query:

select col1, substring(col2, nums.seqnum) as col2
from t cross join
     (select row_number() over (order by (select NULL)) as seqnum
      from Infromation_Schema.columns
     ) nums
where len(col2) <= nums.seqnum

Alternatively, you can do this in a while loop in T-SQL.