User table design

[ozy123]

Hi all,

I'm trying to design an application for a recruitment application. I have two types of users - a coordinator who works for an agency who logs in and posts jobs and searches for canidates. And a candidate who logs in and searches for jobs.

I'm not sure if it is best to have one general user table with fields

*Users*
uid
password
email

and then a table for coordinators

*Coordinators*
first name
last name
dob
agency

and then a table for candidates

*candidates*
professional license number
first name
last name
dob
address
address line 2
town/city
county
post code
country
telephone
mobile

And a table for agencies:

id
name
address
phone
city

All candidates have a professional license number but coordinators do not. So if I put it into one table I would have lots of null values. But there will be massively more candidates than coordinators so it will be less than 1% fields with null values. Not sure whether it is a big issue to have null values?

Thanks in advance

[adam_k]

For some reason I would create 1 table for all 4 of yours and include a type to determine if it's a coordinator or a candidate.

Now for the null values: If you treat null then you'll be just fine. And by treating null I mean using the ISNULL() function and IS NULL as criteria when dealing with the fields that are possible to contain null values.