SQL Server Login is used to Access SQL Server means for Authentication but Database users
are specific to a database to perform database operation based on database role membership and the permission under the tab securables means for Authorization.
After creation of login named SQLLogin as per above figure it will create the user in database Capital with user name SQLLogin with default schema [dbo]
SQL script for SQL Login as per above figure.
CREATE LOGIN [SQLLogin] WITH PASSWORD='random encrypted password', DEFAULT_DATABASE=[master],
DEFAULT_LANGUAGE=[us_english], CHECK_EXPIRATION=OFF, CHECK_POLICY=OFF
We can see in above image SQLLogin is marked as user in database Capital thus it will
Create database user in database Capital using below SQL Script.
CREATE USER [SQLLogin] FOR LOGIN [SQLLogin] WITH DEFAULT_SCHEMA=[dbo]
Once SQL server login and respective database user is created we cannot delete the SQL Server logins if said SQL Login is used to access the SQL Server or database user is still associated with said SQL Login.
Database Role members.
We can create Database user with different types, shown in below figure
As per above image from securables tab we can give required permissions/authorization to database users for database objects (tables/view/sp’s etc.)
SQL Script to create user without SQL Login:
CREATE USER [sqlwologin] WITHOUT LOGIN WITH DEFAULT_SCHEMA=[dbo]