Resolve the functional dependencies to get to 3NF.
Each user has exactly one password, but obviously can have several usernames on various protocols with single passwords.
So the only dependent value which should go in the primary table together with the user name is the password:
Table Users (id_user, username, password)
Table Users_and_Protocols (id_user, protocol, p_username, p_password)
If you want to have better control on the protocol names store them in a reference table: Table Users (id_user, username, password)
Table Users_and_Protocols (id_user, id_protocol, p_username, p_password)
Table Protocols (id_protocol, protocol)
smantscheff
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