SQL Server – NTEXT Columns and String Manipulation

It is not neccesary to modify Jeff Moden's function. I have devised a little bit sophisticated way of achieving the result just using the original function.

First Here it is the original Moden's function: (Source: http://www.sqlservercentral.com/articles/Tally+Table/72993/)

CREATE FUNCTION [dbo].[DelimitedSplit8K]
--===== Define I/O parameters
        (@pString VARCHAR(8000), @pDelimiter CHAR(1))
--WARNING!!! DO NOT USE MAX DATA-TYPES HERE!  IT WILL KILL PERFORMANCE!
RETURNS TABLE WITH SCHEMABINDING AS
 RETURN
--===== "Inline" CTE Driven "Tally Table" produces values from 1 up to 10,000...
     -- enough to cover VARCHAR(8000)
  WITH E1(N) AS (
                 SELECT 1 UNION ALL SELECT 1 UNION ALL SELECT 1 UNION ALL
                 SELECT 1 UNION ALL SELECT 1 UNION ALL SELECT 1 UNION ALL
                 SELECT 1 UNION ALL SELECT 1 UNION ALL SELECT 1 UNION ALL SELECT 1
                ),                          --10E+1 or 10 rows
       E2(N) AS (SELECT 1 FROM E1 a, E1 b), --10E+2 or 100 rows
       E4(N) AS (SELECT 1 FROM E2 a, E2 b), --10E+4 or 10,000 rows max
 cteTally(N) AS (--==== This provides the "base" CTE and limits the number of rows right up front
                     -- for both a performance gain and prevention of accidental "overruns"
                 SELECT TOP (ISNULL(DATALENGTH(@pString),0)) ROW_NUMBER() OVER (ORDER BY (SELECT NULL)) FROM E4
                ),
cteStart(N1) AS (--==== This returns N+1 (starting position of each "element" just once for each delimiter)
                 SELECT 1 UNION ALL
                 SELECT t.N+1 FROM cteTally t WHERE SUBSTRING(@pString,t.N,1) = @pDelimiter
                ),
cteLen(N1,L1) AS(--==== Return start and length (for use in substring)
                 SELECT s.N1,
                        ISNULL(NULLIF(CHARINDEX(@pDelimiter,@pString,s.N1),0)-s.N1,8000)
                   FROM cteStart s
                )
--===== Do the actual split. The ISNULL/NULLIF combo handles the length for the final element when no delimiter is found.
 SELECT ItemNumber = ROW_NUMBER() OVER(ORDER BY l.N1),
        Item       = SUBSTRING(@pString, l.N1, l.L1)
   FROM cteLen l
;

And the query for obtaining the required result (I have created a CTE just for clarity)

DECLARE @string VARCHAR(8000)
SET @string = '!1;100;10;200;0;500;2;1000;30!2;100;3;500;1;2000;5'

;WITH CTE AS
(
SELECT 
SUBSTRING(A.Item,1,CHARINDEX(';',A.Item)-1) As Id, 
B.Item
FROM dbo.DelimitedSplit8K(@string, '!') AS A
CROSS APPLY dbo.DelimitedSplit8K(A.Item, ';') AS B
WHERE A.Item <> '' --to avoid blank first row because the first !
)

SELECT Id, [Value], [Count]
FROM
(
SELECT Id, Item As [Value], 
ROW_NUMBER() OVER(PARTITION BY Id ORDER BY Id) As RowNumber,
LEAD(Item,1,0) OVER(PARTITION BY Id ORDER BY Id) As [Count]
FROM CTE
) As T
WHERE RowNumber % 2 = 0

EDITED: I realized that my solution assummed that id value was ordered or that the order in the original string was not neccesary to be preserved in the result. Below the general solution (note that I changed the first number in the string for testing the situation)

DECLARE @string VARCHAR(8000)
SET @string = '!3;100;10;200;0;500;2;1000;30!2;100;3;500;1;2000;5'
;WITH CTE AS
(
SELECT 
ROW_NUMBER() OVER(ORDER BY (SELECT 0)) As RN,
CAST(SUBSTRING(A.Item,1,CHARINDEX(';',A.Item)-1) AS Varchar(400)) As Id, 
B.Item
FROM dbo.DelimitedSplit8K(@string, '!') AS A
CROSS APPLY dbo.DelimitedSplit8K(A.Item, ';') AS B
WHERE A.Item <> '' --to avoid blank first row because the first !
)

SELECT Id, [Value], [Count]
FROM
(
SELECT Id, Item As [Value], 
ROW_NUMBER() OVER(PARTITION BY Id ORDER BY Id) As RowNumber,
LEAD(Item,1,0) OVER(PARTITION BY Id ORDER BY Id) As [Count]
,FIRST_VALUE(RN) OVER(PARTITION BY Id ORDER BY Id) AS FV
FROM CTE
) As T
WHERE RowNumber % 2 = 0
ORDER BY FV

http://sqlfiddle.com/#!6/31ccd/3

You are trying to put data into a column that is not wide enough for it, as the message suggets.

IIRC Postgre's text columns are open sized much like SQL Server's [N]VARCHAR(MAX) so I suspect there are some long values in there and the target column(s) in your table in SQL Server is a more limited character type (VARCHAR(50) or some such.

That is only a guess though. We can't be any more speicif without much more detail from you. What are the table definitions in Postgres and SQL Server? What tool(s) are you using for to migrate the data (SSIS, plain SQL, something else?)?