How to find word differences between two strings?

Question

I am stuck in one problem.

I want to differentiate words from two strings using SQL Server or Any third party tool.

e.g.:

First String  ==>   "This is for test."
Second String ==>   "This is a for test."

Output        ==>   "a" from second string

or:

First String  ==>   "abc This is for test."
Second String ==>   "This is a for test. This is for test."

Output        ==>   "abc" in first string and "a" from second string

Try to build a method using `String.Replace`. http://stackoverflow.com/questions/7517571/difference-between-two-strings-c-sharp — Nalaka526, May 20 '14 at 07:24
See this: http://stackoverflow.com/questions/208094/how-to-find-difference-between-two-strings — Endrju, May 20 '14 at 07:37
This is not working while First string is longer then second. — AB Vyas, May 20 '14 at 07:37
You could try my .net nuget library, DiffLib, it should be able it give you what you want. — Lasse V. Karlsen, May 20 '14 at 08:40

score 4 · Accepted Answer · answered May 20 '14 at 08:04

Sql-server may not be the best tool, but you could use a script like this, it will split up all the words at the spaces and take the difference between the list words. So a word in 1 text that doesn't exists in the other text will be included in the output, finally the script will concatinate the words:

declare @str1 varchar(2000) = 'abc This is for test. dfg'
declare @str2 varchar(2000) = 'This is a for test. This is for test.'

declare @output1 varchar(2000)
declare @output2 varchar(2000)

SELECT @output1 = case when grp = 1 then coalesce(@output1+ ' ' + col, col)  else @output1 end,
       @output2 = case when grp = 2 then coalesce(@output2+ ' ' + col, col)  else @output2 end
FROM
(values(@str1, @str2, 1),(@str2, @str1, 2)) x(str1, str2, grp)
CROSS APPLY
(
SELECT t.c.value('.', 'VARCHAR(2000)') col
     FROM (
         SELECT x = CAST('<t>' + 
               REPLACE(str1, ' ', '</t><t>') + '</t>' AS XML)
     ) a
     CROSS APPLY x.nodes('/t') t(c)
EXCEPT 
SELECT t.c.value('.', 'VARCHAR(2000)')
     FROM (
         SELECT x = CAST('<t>' + 
               REPLACE(str2, ' ', '</t><t>') + '</t>' AS XML)
     ) a
     CROSS APPLY x.nodes('/t') t(c)
) y
SELECT @output1 FirstString, @output2 SecondString

Result:

FirstString  SecondString
abc dfg      a

How to find word differences between two strings?

1 Answers1

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