User Access, security setting

Hi everybody, My team(Dev. Team) and me are new to Informix and Relational Database system. Traditionally we use to store the User details and password as well as access level in a data file(table) and in each module we, check whether a user have access to certain column(fields) to enable or disable access to each field at runtime. However i am not sure how such a validation can be performed in Informix, whether such validation can be built into the Database Server itself or at each Module and is there a need to create a separate table for users as we used to do or the DBMS provide such facilities? Otherwise such a validation for individual fields(columns) will become tedious. For example, let say, i want to allow user with access level 1 to be able to access a table and all its columns, for update, delete and insert operation, where as those with level 2 access may only perform update to all columns and insert but not delete. Where as for those with level 3, they may only read(display data only) selected columns, may be column no 1 , 2 and 3, but they may not view column no 4. The first level of checking is whether they have permission to read, update, delete or insert, the next level of validation is which columns they may access for update, read and insert operations. If such a validation need to be done in the application what is the best solution? Your help is much appreciated. Syed. -- ---------- Signature ----------- Name: Syed Ibrahim Address: Sapura Advanced Systems Sdn. Bhd, 18th Floor, Menara Tun Razak, Jalan Raja Laut, 50350 Kuala Lumpur, Malaysia Tel: (03) 295-3472, (03) 294-3000 Fax: (03) 294-6587, (03) 293-3154