i have a database ,i want to make it accessible to 3 type of users(admin,applicant,official) with different permissions ....
how can i resolve,what i modifications it gonna need like to table , relations etc

could you specify more about your program so i can help you ? do you have a server to accept request?

@lena1990: hi, i m working on an online project...... Job portal.....where applicant can apply for different jobs and admin put details regarding vacancies, advertisment etc ....so i want to differentiate between them, so how can i do this in Database, via script ?

It sounds to me like the classification of your user accessing the application should not be a database role, but an application role where you store the role itself as a field in your datatabase table.

@Jorgem, dear , i vl try it too if other solutions failed
Thanks !!! :)