Optimal search queries

Question

Following on from my last question Sql Server query performance, and discovering that my method of allowing optional parameters in a search query is sub optimal, does anyone

Answer 1

In your case, the different queries would use the different indexes.

You should define a set of indexes you want to use and write an individual query for each set, replacing OR on indexed fields with UNION ALL:

SELECT  *
FROM    tables
WHERE   A = @ID
        AND (c.Surname = @Surname or @Surname IS NULL)
        AND (HP.phonenumber = @Homphone or @Homephone IS NULL)
        AND (MOB.phonenumber = @Mobile or @Mobile IS NULL)
UNION ALL
SELECT  *
FROM    tables
WHERE   @ID IS NULL
        AND c.Surname = @Surname
        AND (HP.phonenumber = @Homphone or @Homephone IS NULL)
        AND (MOB.phonenumber = @Mobile or @Mobile IS NULL)
UNION ALL
SELECT  *
FROM    tables
WHERE   @ID IS NULL
        AND @Surname IS NULL
        AND (HP.phonenumber = @Homphone or @Homephone IS NULL)
        AND (MOB.phonenumber = @Mobile or @Mobile IS NULL)