Sql-server – Single query approach to split and copy string values in a column

sql serversql-server-2008substring

This is a part of my previous question.

I have the below logic to split a string value from a column in table tblProjects as below:

SELECT  @Docs = Documents FROM tblProjects WHERE ID = @ID 
SET @Docs = @Docs + '$'
SET @pos = 0
SET @len = 0

WHILE CHARINDEX('$', @Docs, @pos + 1)>0
BEGIN
  SET @len = CHARINDEX('$', @Docs, @pos + 1) - @pos
  SET @value = SUBSTRING(@Docs, @pos, @len)

  IF CHARINDEX('|', @value) >0
  BEGIN
    SELECT  @type = SUBSTRING(@value, 1, CHARINDEX('|', @value) - 1),
            @name = SUBSTRING(@value, CHARINDEX('|', @value) + 1, 200)
    INSERT INTO tblDocuments VALUES(@ID, @value, @type, @name)
  END   

  SET @pos = CHARINDEX('$', @Docs, @pos + @len) +1
END

A sample input would be

insert into tblProjects(ID, Documents) 
values('P_1', 'gdgfg|jkkgk$bkgkkj|kjgkgk$vjffj|Khkgjhg$jkgkvghv|kbkghhkgk');

I need to split the Documents string and insert the values into a separate table. Values delimited by | should go into separate columns of the same row, whereas values for a particular row are delimited by $.

Is there a single query method to complete this operation, for all rows in the table, in the minimum possible time?

Best Answer

You should make use of a split string function.

select left(S.Item, charindex('|', S.Item) - 1),
       stuff(S.Item, 1, charindex('|', S.Item), '')
from dbo.tblProjects as P
  cross apply dbo.SplitString(P.Documents, '$') as S;

Aaron Bertrand blogged about some of the alternatives you have in Split strings the right way – or the next best way

Related Solutions

Sql-server – Combine column from multiple rows into single row

This is relatively trivial to do with a correlated subquery. You can't use the COALESCE method highlighted in the blog post you mention unless you extract that to a user-defined function (or unless you only want to return one row at a time). Here is how I typically do this:

DECLARE @x TABLE 
(
  id INT, 
  row_num INT, 
  customer_code VARCHAR(32), 
  comments VARCHAR(32)
);

INSERT @x SELECT 1,1,'Dilbert','Hard'
UNION ALL SELECT 1,2,'Dilbert','Worker'
UNION ALL SELECT 2,1,'Wally','Lazy';

SELECT id, customer_code, comments = STUFF((SELECT ' ' + comments 
    FROM @x AS x2 WHERE id = x.id
     ORDER BY row_num
     FOR XML PATH('')), 1, 1, '')
FROM @x AS x
GROUP BY id, customer_code
ORDER BY id;

If you have a case where the data in comments could contain unsafe-for-XML characters (>, <, &), you should change this:

     FOR XML PATH('')), 1, 1, '')

To this more elaborate approach:

     FOR XML PATH(''), TYPE).value(N'(./text())[1]', N'varchar(max)'), 1, 1, '')

(Be sure to use the right destination data type, varchar or nvarchar, and the right length, and prefix all string literals with N if using nvarchar.)

Sql-server – T SQL Table Valued Function to Split a Column on commas

Re-worked it slightly...

DECLARE @FoundIndex INT
DECLARE @ReturnValue VARCHAR(MAX)

SET @FoundIndex = CHARINDEX(@delimiter, @String)

WHILE (@FoundIndex <> 0)
BEGIN
      SET @ReturnValue = SUBSTRING(@String, 0, @FoundIndex)
      INSERT @SplitValues (Asset_ID) VALUES (@ReturnValue)
      SET @String = SUBSTRING(@String, @FoundIndex + 1, len(@String) - @FoundIndex)
      SET @FoundIndex = CHARINDEX(@delimiter, @String)
END

INSERT @SplitValues (Asset_ID) VALUES (@String)

RETURN

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