like operator issue

Question

I have a dom table

select * from dom

dom table details:

id    name     skills
1     do         


        

Answer 1

You need to use full text search or redesign your schema by extracting skills into a separate table and have M:N relation between Skill and Dom tables.

Answer 2

in order to handle all possible cases (beginning of string, end of string, between 2 delimiters) you would need the inefficient (can't use an index)

SELECT *
FROM   dom
WHERE  CONCAT(',', skills, ',') LIKE '%,C,%'
       AND CONCAT(',', skills, ',') LIKE '%,C++,%' 

The best answer would be to put your database into at least first Normal Form!

A separate skills table and skills/person matrix table is much more efficient to search and easier to work with (e.g. removing an individual skill)

If you need a query that would bring back records in doms who match both C and C++ (assuming the same schema as jimmy_keen's answer) this could be done with a self join to get the intersection, the intersect operator, or using other relational division techniques such as

SELECT d.name
FROM   dom d
       JOIN dom_skills ds
         ON ( d.id = ds.id_dom )
       JOIN skills s
         ON ( ds.id_skill = s.id )
WHERE  s.name IN ( 'C', 'C++' )
GROUP  BY d.id,
          s.id,
          d.name
HAVING COUNT(DISTINCT s.name) = 2 

Answer 3

Skills column looks like something you might want to map with many-to-many relationship with your original "dom" table. For example:

SKILLS      DOM         DOM_SKILLS
id | name   id | name   id_dom | id_skill
---'-----   ---'-----   -------'---------
 1 | C       1 | dom        1  |  1 
 2 | C++                    1  |  2

This way, your query might look bit more complex...

SELECT d.name, s.name 
FROM dom d 
JOIN dom_skills ds ON (d.id = ds.id_dom) 
JOIN skills s ON (ds.id_skill = s.id)
WHERE s.name LIKE '%C%' OR s.name LIKE '%C++'

...but your schema will be easier to manage (think about duplicate entries, updating etc.. the normal form stuff, which is at the moment violated by your schema).