In an APP with many accounts How do i get users to open only their accounts at login?

[mostwanted]

I want to create an application that has 2 accounts, account_A & account_B and a login page, i want every user to be directed to their specific account at login, account_A user should see only all the account_A details and information when they successfully login and not account_B information. How can i achieve this?

Thank you.