SQL server matching two table on a column - sql

Question

I have two tables one storing user skills another storing skills required for a job. I want to match how many skills a of each user matches with a job.
The table structure is
Table1: User_Skills
| ID | User_ID | Skill |
---------------------------
| 1 | 1 | .Net |
---------------------------
| 2 | 1 | Software|
---------------------------
| 3 | 1 | Engineer|
---------------------------
| 4 | 2 | .Net |
---------------------------
| 5 | 2 | Software|
---------------------------
Table2: Job_Skills_Requirement
| ID | Job_ID | Skill |
--------------------------
| 1 | 1 | .Net |
---------------------------
| 2 | 1 | Engineer|
---------------------------
| 3 | 1 | HTML |
---------------------------
| 4 | 2 | Software|
---------------------------
| 5 | 2 | HTML |
---------------------------
I was trying to have comma separated skills and compare but these can be in different order.
Edit
All the answers here are excellent. The result I am looking for is matching all jobs with all users as later on I will match other properties as well.

Answer 1

You could join the tables by the skill columns and count the matches:
SELECT user_id, job_id, COUNT(*) AS matching_skills
FROM user_skills u
JOIN job_skills_requirement j ON u.skill = j.skill
GROUP BY user_id, job_id
EDIT:
IF you want to also show users and jobs that have no matching skills, you can use a full outer join instead.
SELECT user_id, job_id, COUNT(*) AS matching_skills
FROM user_skills u
FULL OUTER JOIN job_skills_requirement j ON u.skill = j.skill
GROUP BY user_id, job_id
EDIT 2:
As Jiri Tousek commented, the above query will produce nulls where there's no match between a user and a job. If you want a full Cartesian products between them, you could use (abuse?) the cross join syntax and count how many skills actually match between each user and each job:
SELECT user_id,
job_id,
COUNT(CASE WHEN u.skill = j.skill THEN 1 END) AS matching_skills
FROM user_skills u
CROSS JOIN job_skills_requirement j
GROUP BY user_id, job_id

Answer 2

If you want to match all users and all jobs, then Mureinik's otherwise excellent answer is not correct.
You need to generate all the rows first, which I would do using a cross join and then count the matching ones:
select u.user_id, j.job_id, count(jsr.job_id) as skills_in_common
from users u cross join
jobs j left join
user_skills us
on us.user_id = u.user_id left join
Job_Skills_Requirement jsr
on jsr.job_id = j.job_id and
jsr.skill = us.skill
group by u.user_id, j.job_id;
Note: This assumes the existence of a users and a jobs table. You can of course generate these using subqueries.

Answer 3

WITH User_Skills(ID,User_ID,Skill)AS(
SELECT 1,1,'.Net' UNION ALL
SELECT 2,1,'Software' UNION ALL
SELECT 3,1,'Engineer' UNION ALL
SELECT 4,2,'.Net' UNION ALL
SELECT 5,2 ,'Software'
),Job_Skills_Requirement(ID,Job_ID,Skill)AS(
SELECT 1,1,'.Net' UNION ALL
SELECT 2,1,'Engineer' UNION ALL
SELECT 3,1,'HTML' UNION ALL
SELECT 4,2,'Software' UNION ALL
SELECT 5,2 ,'HTML'
),Job_User_Skill AS (
SELECT j.Job_ID,u.User_ID,u.Skill
FROM Job_Skills_Requirement AS j INNER JOIN User_Skills AS u ON u.Skill=j.Skill
)
SELECT jus.Job_ID,jus.User_ID,COUNT(jus.Skill),STUFF(c.Skills,1,1,'') AS Skill
FROM Job_User_Skill AS jus
CROSS APPLY(SELECT ','+j.Skill FROM Job_User_Skill AS j WHERE j.Job_ID=jus.Job_ID AND j.User_ID=jus.User_ID FOR XML PATH('')) c(Skills)
GROUP BY jus.Job_ID,jus.User_ID,c.Skills
ORDER BY jus.Job_ID
Job_ID User_ID Skill
----------- ----------- ----------- -------------
1 1 2 .Net,Engineer
1 2 1 .Net
2 1 1 Software
2 2 1 Software