SQL Server Full Text Search - Weighting Certain Columns Over Others - sql-server

Question

If I have the following full text search query:
SELECT *
FROM dbo.Product
INNER JOIN CONTAINSTABLE(Product, (Name, Description, ProductType), 'model') ct
ON ct.[Key] = Product.ProductID
Is it possible to weigh the columns that are being searched?
For example, I care more about the word model appearing in the Name column than I do the
Description or ProductType columns.
Of course if the word is in all 3 columns then I would expect it to rank higher than if it was just in the name column. Is there any way to have a row rank higher if it just appears in Name vs just in Description/ProductType?

Answer 1

You can do something like the following query. Here, WeightedRank is computed by multiplying the rank of the individual matches. NOTE: unfortunately I don't have Northwind installed so I couldn't test this, so look at it more like pseudocode and let me know if it doesn't work.
declare #searchTerm varchar(50) = 'model';
SELECT 100 * coalesce(ct1.RANK, 0) +
10 * coalesce(ct2.RANK, 0) +
1 * coalesce(ct3.RANK, 0) as WeightedRank,
*
FROM dbo.Product
LEFT JOIN
CONTAINSTABLE(Product, Name, #searchTerm) ct1 ON ct1.[Key] = Product.ProductID
LEFT JOIN
CONTAINSTABLE(Product, Description, #searchTerm) ct2 ON ct2.[Key] = Product.ProductID
LEFT JOIN
CONTAINSTABLE(Product, ProductType, #searchTerm) ct3 ON ct3.[Key] = Product.ProductID
order by WeightedRank desc

Answer 2

Listing 3-25. Sample Column Rank-Multiplier Search of Pro Full-Text Search in SQL Server 2008
SELECT *
FROM (
SELECT Commentary_ID
,SUM([Rank]) AS Rank
FROM (
SELECT bc.Commentary_ID
,c.[RANK] * 10 AS [Rank]
FROM FREETEXTTABLE(dbo.Contributor_Birth_Place, *, N'England') c
INNER JOIN dbo.Contributor_Book cb ON c.[KEY] = cb.Contributor_ID
INNER JOIN dbo.Book_Commentary bc ON cb.Book_ID = bc.Book_ID
UNION ALL
SELECT c.[KEY]
,c.[RANK] * 5
FROM FREETEXTTABLE(dbo.Commentary, Commentary, N'England') c
UNION ALL
SELECT ac.[KEY]
,ac.[RANK]
FROM FREETEXTTABLE(dbo.Commentary, Article_Content, N'England') ac
) s
GROUP BY Commentary_ID
) s1
INNER JOIN dbo.Commentary c1 ON c1.Commentary_ID = s1.Commentary_ID
ORDER BY [Rank] DESC;

Answer 3

Similar to Henry's solution but simplified, tested and using the details the question provided.
NB: I ran performance tests on both the union and left join styles and found the below to require far less logical reads on the union style below with my datasets YMMV.
declare #searchTerm varchar(50) = 'model';
declare #nameWeight int = 100;
declare #descriptionWeight int = 10;
declare #productTypeWeight int = 1;
SELECT ranksGroupedByProductID.*, outerProduct.*
FROM (SELECT [key],
Sum([rank]) AS WeightedRank
FROM (
-- Each column that needs to be weighted separately
-- should be added here and unioned with the other queries
SELECT [key],
[rank] * #nameWeight as [rank]
FROM Containstable(dbo.Product, [Name], #searchTerm)
UNION ALL
SELECT [key],
[rank] * #descriptionWeight as [rank]
FROM Containstable(dbo.Product, [Description], #searchTerm)
UNION ALL
SELECT [key],
[rank] * #productTypeWeight as [rank]
FROM Containstable(dbo.Product, [ProductType], #searchTerm)
) innerSearch
-- Grouping by key allows us to sum each ProductID's ranks for all the columns
GROUP BY [key]) ranksGroupedByProductID
-- This join is just to get the full Product table columns
-- and is optional if you only need the ordered ProductIDs
INNER JOIN dbo.Product outerProduct
ON outerProduct.ProductID = ranksGroupedByProductID.[key]
ORDER BY WeightedRank DESC;