store multiple values in single column in mysql

Question

table name :internship ,now i want to store "skill_required"for company name XYZ like skill are: php , java etc mow Question is at the time of company registration i have to specify text of or check box..etc and how to store it in database ?with id ?like 1 for php 2 for java

2nd. when student search for internship then in field of interest he specify php other student specify java ,so then company xyz must be display for both student search as company is providing internship on php and java both,so how to retrieve that form database,? there should be separate table for skills with skill name and skill id?

Answer 1

You should have a separate table linking each company to all skills they require, for example the Company table:

CompanyId  CompanyName
_________  ___________
1          BobCo
2          PeteCo
...

...and skills required in your Internship table:

CompanyID  SkillID
_________  _______
1          1
1          2
2          1
...

...and then you could have a separate Skill table mapping skill IDs to skill names:

SkillID  SkillName
_______  _________
1        PHP
2        Java
3        MySQL
...

For example, if Java is skill 2, you could do:

SELECT CompanyID FROM Internship WHERE SkillID=2;

That query returns the companies that require Java. Alternatively, a more complex query:

SELECT CompanyName 
FROM Company JOIN Internship USING(CompanyID)
  JOIN Skill USING(SkillID)
WHERE SkillName = 'Java'

You should not put multiple values in a single column, because doing so breaks first normal form. Have a look at that link for examples of the problems you're likely to come across, and how to fix them.