"MSSql DB On Windows" pattern is not setting status (install_status) to installed when discovery identifies that the Instance is properly discovered.

Some cmdb_ci_db_mssql_instance records are left as "Absent".

This is because the pattern is not updating install_status field.

The field is set to default field value "Installed" during the first discovery.

If for any reason the Status field value is changed (e.g. due to deletion strategy, it may be changed to "Absent"), then the following discovery will not change it back to "Installed".

> Run discovery to a Windows Server that's hosting MS SQL

> Change status of discovered cmdb_ci_db_mssql_instance record to Absent

> Run discovery again to the Windows Server, status of cmdb_ci_db_mssql_instance is still showing Absent

The fix is to modify the pattern to update "install_status" field to value "1":

Pattern Designer > MSSql DB On Windows > 
click on "Identification for MS SQL Server" > step 56. Create the main CI > click on plus sign to add an additional field: 
name: install_status, value: 1
Save and publish the pattern.

now go back to MSSql DB On Windows pattern, click on "Identification for MS SQL or TCP with port" > step 27. create the main CI > click on plus sign to add an additional field: 
name: install_status, value: 1
Save and publish the pattern.