[support] Doubt on Index and Primary key

[Metzler, David]

Think about how you would write a query to say who has the skill set x?   You can't really do it, cause you've got to change what table you select based on what you're looking for?  How much php code will you have to change to a).  Add a skill set?   B.) add a work domain? 

 

Rather design a table for user skill sets with the columns:

 

Uid, skill_set_id

 

And a lookup table to define skill sets and their categories and their relavent work domains: 

 

Skill_set_id, skill_set_descr, work_domain

 

If you need to create 50 tables for modeling a concept you probably aren't normalized. There are other approaches, but this is probably the simplest. 

 

Dave

 

 

 

 

________________________________

From: support-bounces at drupal.org [mailto:support-bounces at drupal.org] On Behalf Of Austin Einter
Sent: Thursday, March 24, 2011 6:58 PM
To: support at drupal.org; pierre.rineau at makina-corpus.com
Subject: Re: [support] Doubt on Index and Primary key

 

Hi Pierre, David, Ursula

Thanks for excellent piece of information. I just went through basic database concepts like indexing, join, normalisation and tried to analyse how can I apply these for my job registration site implementation.

 

After understanding a bit on normalisation and join, I have comeup with below approach for this specific case.

 

Instead of having a single table, and comma separated values in table cells , I am going to split it multiple tables.

I am attaching a table.xls file , please have a look. 

 

In that excel sheet, I have the main table, and I have broken the main table into 9 different tables. But I hope it need to be broken into more number of tables, depends on how many  different kind of work domains are there. It may go to 50+ tables.

 

Examples for work domains are - Web, PSTN, VoIP, NetworkManagement, GSM, Datbase, BoardDesign etc.

 

So how many work domains are there, those many tables will be there. In those tables, a coulmn will represent a particular skill set.

 

Say under Web Tables, coulmns can be HTML, PHP, Web2.0, Drupal, ASP, etc

And under NetworkManagement table, NMS and SNMP can be coulmns.

 

In table cells, I will keep either 1 or 0, depending on the person has that skill or not.

 

 

 Example: Lets say User 2 knows NMS and SNMP, User 3 knows only SNMP, User4 knows only SNMP, then the table will look as below.

 

UID

NMS

SNMP

2

1

1

3

0

1

4

0

1

 

 

As first time I am  doing this, I might be wrong. If so, kindly let me know.

 

Best Regards

Austin.

 

 

 



 

On Fri, Mar 18, 2011 at 8:54 PM, Pierre Rineau <pierre.rineau at makina-corpus.com> wrote:

Le vendredi 18 mars 2011 à 08:15 -0700, Metzler, David a écrit :

> Pierre is spot on here.
>
> That is why most dbas would advise against storing this data in a comma separated list in a single field.  An index cannot really be used to search within the text cause you are forcing to examine every row anyway.  I can't programtically say lets start with the N's, now is there a nokia in there (that's an oversimplification intentionally to make a point). Rather I would make a single skill table that housed the values. If UID is the primary key for the resume, then you'd make a table with
>
> On a separate note, you do understand that the site that you're talking about building could be done without you writing ANY code? Basically the site you've described can be implemented with content_profile, cck and views modules, allowing you to build custom content types that are tied (one per user).  You could then use taxonomys for skill sets an all this would be written for you?
>
> Dave

Dave is right about the fact this simple business stuff could be done in
many ways using D6 existing modules (even only with core and taxonomy)
or D7 fields.

But, if you really want to learn technical aspects of SQL and/or Drupal
development, this is a good thing to start with this kind of simple
business stuff.


Pierre.


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