How to extract every 7 characters of an nvarchar into another table? - sql-server

Question

I have an nvarchar(200) called ColumnA in Table1 that contains, for example, the value:
ABCDEFGHIJKLMNOPQRSTUVWXYZ
I want to extract every 7 characters into Table2, ColumnB and end up with all of these values below.
ABCDEFG
BCDEFGH
CDEFGHI
DEFGHIJ
EFGHIJK
FGHIJKL
GHIJKLM
HIJKLMN
IJKLMNO
JKLMNOP
KLMNOPQ
LMNOPQR
MNOPQRS
NOPQRST
OPQRSTU
PQRSTUV
QRSTUVW
RSTUVWX
STUVWXY
TUVWXYZ
[Not the real table and column names.]
The data is being loaded to Table1 and Table2 in an SSIS Package, and I'm puzzling whether it is better to do the string handling in TSQL in a SQL Task or parse out the string in a VB Script Component.
[Yes, I think we're the last four on the planet using VB in Script Components. I cannot persuade the other three that this C# thing is here to stay. Although, maybe it is a perfect time to go rogue.]

Answer 1

You can use a recursive CTE calculating the offsets step by step and substring().
WITH
cte
AS
(
SELECT 1 n
UNION ALL
SELECT n + 1 n
FROM cte
WHERE n + 1 <= len('ABCDEFGHIJKLMNOPQRSTUVWXYZ') - 7 + 1
)
SELECT substring('ABCDEFGHIJKLMNOPQRSTUVWXYZ', n, 7)
FROM cte;
db<>fiddle

Answer 2

If you have a physical numbers table, this is easy. If not, you can create a tally-on-the-fly:
DECLARE #string VARCHAR(100)='ABCDEFGHIJKLMNOPQRSTUVWXYZ';
--We create the tally using ROW_NUMBER against any table with enough rows.
WITH Tally(Nmbr) AS
(SELECT TOP(LEN(#string)-6) ROW_NUMBER() OVER(ORDER BY (SELECT NULL)) FROM master..spt_values)
SELECT Nmbr
,SUBSTRING(#string,Nmbr,7) AS FragmentOf7
FROM Tally
ORDER BY Nmbr;
The idea in short:
The tally returns a list of numbers from 1 to n (n=LEN(#string)-6). This Number is used in SUBSTRING to define the starting position.

Answer 3

You can do it with T-SQL like this:
DECLARE C CURSOR LOCAL FOR SELECT [ColumnA] FROM [Table1]
OPEN C
DECLARE #Val nvarchar(200);
FETCH NEXT FROM C into #Val
WHILE ##FETCH_STATUS = 0 BEGIN
DECLARE #I INTEGER;
SELECT #I = 1;
WHILE #I <= LEN(#vAL)-6 BEGIN
PRINT SUBSTRING(#Val, #I, 7)
SELECT #I = #I + 1
END
FETCH NEXT FROM C into #Val
END
CLOSE C

Answer 4

Script Component solution
Assuming that the input Column name is Column1
Add a script component
Open the script component configuration form
Go to Inputs and Outputs Tab
Click on the Output icon and set the Synchronous Input property to None
Add an Output column (example outColumn1)
In the Script editor, use a similar code in the row processing function:
Dim idx as integer = 0
While Row.Column1.length > idx + 7
Output0Buffer.AddRow()
Output0Buffer.outColumn1 = Row.
Column1.Substring(idx,7)
idx +=1
End While