A Common Username for Both Database hosted in Azure
You can create Login in master database using syntax ..

CREATE LOGIN &lt;SQL_login_name, sysname, login_name&gt; 
    WITH PASSWORD = '&lt;password, sysname, Change_Password&gt;' 
GO


and then create user in individual databases using syntax

CREATE USER &lt;user_name, sysname, user_name&gt;
    FOR LOGIN &lt;login_name, sysname, login_name&gt;
    WITH DEFAULT_SCHEMA = &lt;default_schema, sysname, dbo&gt;
GO

GRANT SELECT  TO &lt;user_name&gt;


This can be done via SSMS from local machine or VM. I believe you can achieve this using Query Editor in Azure as it does not allow switching context to master database .