[SOLVED] How add additional data to a cell?

[sorenchr]

Hi, i have a fairly simple table in my DB:

 

Username

Tags

testuser1

test, bla

testuser2

abc, bla2

 

Im using a php page, which allows the user to add additional tags to their username. So my question is, what mysql query do i use when i want to add additional data to their tags? I only know of UPDATE, but that one replaces all the existing data with the newly entered.

 

To illustrate my question, I, as "testuser1", add the tag "christmas" to my taglist, so that the new table looks like this:

 

Username

Tags

testuser1

test, bla, christmas

testuser2

abc, bla2

 

Best regards

Soren

[Daniel0]

You shouldn't do it this way. The fact that you are having issues manipulating the data is a testimony to this. What you're looking at is a many-to-many relationship which is made by having a third linking table giving you these tables:

 

users

- user_id

- username

 

tags

- tag_id

- name

 

tags_users

- tag_id

- user_id

 

To get user #568's tags you can do this:

SELECT t.name
  FROM tags_users link
  INNER JOIN users u
    ON u.user_id = link.user_id
  INNER JOIN tags t
    ON t.tag_id = link.tag_id
  WHERE u.user_id = 568;

 

And as for your problem, adding a tag to a user is a simple INSERT operation (you'd have to insert a new tag into the tags table as well if it's not a new tag).

[sorenchr]

Thank you, we actually had about data modelling in class today, can't believe the "register" trick went over my head