Word matching in SQL Server

Question

I have a requirement to provide a suggested match between data in two database tables. The basic requirement is; - A \"match\" should be suggested for the highest number of

Answer 1

I've used sys.dm_fts_parser below to split the sentences into words. There are plenty of TSQL split functions around if you are not on SQL Server 2008 or find this isn't suitable for some reason.

The requirement that each A.id can only be paired with a B.id that hadn't been used previously and vice-versa isn't one I could think of an efficient set based solution for.

;WITH A(Id, sentence) As
(
  SELECT 1,'What other text in here'    UNION ALL
  SELECT 2,'What am I doing here'       UNION ALL 
  SELECT 3,'I need to find another job' UNION ALL 
  SELECT 4,'Other text in here'         
),
B(Id, sentence) As
(
 SELECT  5,'Other text in here'          UNION ALL
 SELECT  6,'I am doing what here'        UNION ALL
 SELECT  7,'Purple unicorns'             UNION ALL
 SELECT  8,'What are you doing in here'
),  A_Split
     AS (SELECT Id AS A_Id,
                display_term,
                COUNT(*) OVER (PARTITION BY Id) AS A_Cnt
         FROM   A
                CROSS APPLY 
                   sys.dm_fts_parser('"' + REPLACE(sentence, '"', '""')+'"',1033, 0,0)),

     B_Split
     AS (SELECT Id AS B_Id,
                display_term,
                COUNT(*) OVER (PARTITION BY Id) AS B_Cnt
         FROM   B
                CROSS APPLY 
                   sys.dm_fts_parser('"' + REPLACE(sentence, '"', '""')+'"',1033, 0,0)),
     Joined
     As (SELECT A_Id,
                B_Id,
                B_Cnt,
                Cnt = COUNT(*),
                CAST(COUNT(*) as FLOAT)/B_Cnt AS PctMatchBToA,
                CAST(COUNT(*) as FLOAT)/A_Cnt AS PctMatchAToB
         from   A_Split A
                JOIN B_Split B
                  ON A.display_term = B.display_term
         GROUP  BY A_Id,
                   B_Id,
                   B_Cnt,
                   A_Cnt)
SELECT IDENTITY(int, 1, 1) as id, *
INTO   #IntermediateResults
FROM   Joined
ORDER  BY PctMatchBToA DESC,
          PctMatchAToB DESC

DECLARE @A_Id INT,
        @B_Id INT,
        @Cnt  INT

DECLARE @Results TABLE (
  A_Id INT,
  B_Id INT,
  Cnt  INT)

SELECT TOP(1) @A_Id = A_Id,
              @B_Id = B_Id,
              @Cnt = Cnt
FROM   #IntermediateResults
ORDER  BY id

WHILE ( @@ROWCOUNT > 0 )
  BEGIN

      INSERT INTO @Results
      SELECT @A_Id,
             @B_Id,
             @Cnt

      DELETE FROM #IntermediateResults
      WHERE  A_Id = @A_Id
              OR B_Id = @B_Id

      SELECT TOP(1) @A_Id = A_Id,
                    @B_Id = B_Id,
                    @Cnt = Cnt
      FROM   #IntermediateResults
      ORDER  BY id
  END

DROP TABLE #IntermediateResults

SELECT *
FROM   @Results
ORDER  BY A_Id  

Returns

A_Id        B_Id        Cnt
----------- ----------- -----------
1           8           3
2           6           5
4           5           4