SQL query for create a sql user for the database

role.sql

-- This file should execute in the database that you want to assign this user

CREATE USER webappuser
    FOR LOGIN webappuser
GO

EXEC sp_addrolemember N'db_datareader', N'webappuser'
EXEC sp_addrolemember N'db_datawriter', N'webappuser'
EXEC sp_addrolemember N'db_ddladmin', N'webappuser'
GO

user.sql

-- We need to execute this query in master database in order to assign it to others databases

CREATE LOGIN sampleuser WITH PASSWORD = 'yourpassword' GO