title: SQL Server database missing INFORMATION_SCHEMA and sys users
body: <p>I have a database that has been restored into my environment from a production website for development.  The original database was SQL Server 2016, and it was originally 2016 in my development environment too.  I used Red Gate SQL Compare/Data Compare to migrate it to 2014 for maximum compatibility across environments.</p>
  
  <p>In both the restored SQL Server 2016 and 2014 environments there are two users listed but have an icon indicating that they are missing (red X over them).  </p>
  
  <p>If I run a query to list all users in the database, they indeed appear to be missing. Example queries are below.</p>
  
  <pre><code>select suser_sname(owner_sid) as 'Owner', state_desc, * 
  from sys.databases 
  order by [name]
  
  select * 
  from master.sys.server_principals  
  order by [name]
  </code></pre>
  
  <p>The two user accounts in question are <code>INFORMATION_SCHEMA</code> and <code>sys</code>. These appear to be built-in user accounts, per MS documentation below.</p>
  
  <p><a href="https://docs.microsoft.com/en-us/sql/relational-databases/security/authentication-access/principals-database-engine?view=sql-server-2017#informationschema-and-sys-users-and-schemas" rel="nofollow noreferrer">https://docs.microsoft.com/en-us/sql/relational-databases/security/authentication-access/principals-database-engine?view=sql-server-2017#informationschema-and-sys-users-and-schemas</a></p>
  
  <p>Why would these accounts be missing after restoring the database?</p>
  
  <p>Do I need to add them? If yes, how do I do that safely? According to the steps provided in the documentation below, they aren't listed as orphaned accounts.</p>
  
  <p><a href="https://docs.microsoft.com/en-us/sql/sql-server/failover-clusters/troubleshoot-orphaned-users-sql-server?view=sql-server-2017" rel="nofollow noreferrer">https://docs.microsoft.com/en-us/sql/sql-server/failover-clusters/troubleshoot-orphaned-users-sql-server?view=sql-server-2017</a></p>
  
  <p>What is the risk of not recreating these user accounts?</p>