Question

In my mssql database I have a table containing articles(id, name, content) a table containing keywords(id, name) and a link table between articles and keywords ArticleKeywords(articleId, keywordID, count). Count is the number of occurrences of that keyword in the article.

How can I write a SP that gets a list of comma separated strings and gives me the articles that have this keywords ordered by the number of occurrences of the keywords in the article?
If an article contains more keywords I want to sum the occurrences of each keyword.

Thanks, Radu

Answer 1

Although it isn’t completely clear to me what the source of your comma-separated string is, I think what you want is an SP that takes a string as input and produces the desired result:

CREATE PROC KeywordArticleSearch(@KeywordString NVARCHAR(MAX)) AS BEGIN...

The first step is to verticalize the comma-separated string into a table with the values in rows. This is a problem that has been extensively treated in this question and another question, so just look there and choose one of the options. Whichever way you choose, store the results in a table variable or temp table.

DECLARE @KeywordTable TABLE (Keyword NVARCHAR(128))
-- or alternatively...
CREATE TABLE #KeywordTable (Keyword NVARCHAR(128))

For lookup speed, it is even better to store the KeywordID instead so your query only has to find matching ID’s:

DECLARE @KeywordIDTable TABLE (KeywordID INT)
INSERT INTO @KeywordTable 
    SELECT K.KeywordID FROM SplitFunctionResult S 
    -- INNER JOIN: keywords that are nonexistent are omitted
    INNER JOIN Keywords K ON S.Keyword = K.Keyword

Next, you can go about writing your query. This would be something like:

SELECT articleId, SUM(count)
FROM ArticleKeywords AK
WHERE K.KeywordID IN (SELECT KeywordID FROM @KeywordIDTable)
GROUP BY articleID

Or instead of the WHERE you could use an INNER JOIN. I don’t think the query plan would be much different.