Question

So I have two users a mentor and a mentee.

I want to show the mentee a list of mentors based on matching their skills.

So the registration would be a bunch of checkboxes which say…

Mentee sees:

I need help with

[] Branding
[] Marketing
[] Legal stuff

Mentor sees:

My expertise

[] Branding
[] Marketing
[] Legal stuff

Is there a SQL-server query to match these guys up based on most commonality?

Hope this all makes sense :\

Cheers

Answer 1

How about starting with something like this:

declare @Users as Table ( UserId Int Identity, UserName VarChar(10), Mentor Bit )
declare @Skills as Table (SkillId Int Identity, Skill VarChar(10) )
declare @UserSkills as Table ( UserId Int, SkillId Int )

insert into @Users ( UserName, Mentor ) values ( 'Einstein', 1 ), ( 'Dilbert', 0 ), ( 'Marie', 1 ), ( 'The Fonz', 1 )
insert into @Skills ( Skill ) values ( 'Arithmetic' ), ( 'Chemistry' ), ( 'Dancing' )
insert into @UserSkills ( UserId, SkillId ) values
  ( 1, 1 ), ( 1, 3 ),
  ( 2, 1 ), ( 2, 3 ),
  ( 3, 1 ), ( 3, 2 ), ( 3, 3 ),
  ( 4, 3 )

-- All users.
select U.*, S.*
  from @Users as U inner join
    @UserSkills as US on US.UserId = U.UserId inner join
    @Skills as S on S.SkillId = US.SkillId
  order by U.Mentor, U.UserName, S.Skill

-- Matches for user 2.
--   Should validate that they are not a mentor.
declare @StudentId as Int = 2
select UM.*, S.*,
  ( select count(42) from @UserSkills as USM inner join
    @UserSkills as USS on USS.SkillId = USM.SkillId and USS.UserId = @StudentId and USM.UserId = UM.UserId ) as 'MatchCount'
  from @Users as UM inner join
    @UserSkills as USM on USM.UserId = UM.UserId and UM.Mentor = 1 inner join
    @Skills as S on S.SkillId = USM.SkillId inner join
    @UserSkills as USS on USS.SkillId = USM.SkillId and USS.UserId = @StudentId
  order by ( select count(42) from @UserSkills as USM inner join
    @UserSkills as USS on USS.SkillId = USM.SkillId and USS.UserId = @StudentId and USM.UserId = UM.UserId ) desc,
    UM.UserName, S.Skill