Can I access SQL server data tables from field maps?

[TomMagdaleno]

I'm trying to implement the sign management solution.  But we already have thousands of signs and maintenance records in SQL.  I would like to leave the data there if possible.  Is their a way to get access to this server data and tables through portal?    Or am I better off just copying everything over to Portal?  I think its a bit too much data to store on Online.  

[HannesVogel]

If you have a ArcGIS Enterprise Portal you can publish map-/featureservices referencing Enterprise Geodatabases (SDE) based on SQL. You can add such services in a Webmap to see/edit it in Field Maps.

[HannesVogel]

but it is not a requirement to have Enterprise Geodatabase, "normal" SQL Databases can be referenced as well for read only.