ArcGIS Pro 2.6 API Reference Guide
GDBProjectItem Class
Members  Example 

ArcGIS.Desktop.Catalog Namespace : GDBProjectItem Class
Represents a database project item
Object Model
GDBProjectItem ClassItem ClassDatastore ClassTimeInstant Class
Syntax
public sealed class GDBProjectItem : ArcGIS.Desktop.Internal.Catalog.ProjectItemInfoCrawl, ArcGIS.Desktop.Core.IMetadata, ArcGIS.Desktop.Core.IProjectItem, System.ComponentModel.INotifyPropertyChanged  
Public NotInheritable Class GDBProjectItem 
   Inherits ArcGIS.Desktop.Internal.Catalog.ProjectItemInfoCrawl
   Implements ArcGIS.Desktop.Core.IMetadata, ArcGIS.Desktop.Core.IProjectItem, System.ComponentModel.INotifyPropertyChanged 
Remarks

A database project item is a file geodatabase, enterprise geodatabase, SQLite database, or a geopackage that has been added to the current project.

Example
/// Add a file geodatabase or a SQLite or enterprise database connection to a project
Item gdbToAdd = folderToAdd.GetItems().FirstOrDefault(folderItem => folderItem.Name.Equals("CountyData.gdb"));
var addedGeodatabase = await QueuedTask.Run(() => Project.Current.AddItem(gdbToAdd as IProjectItem));
Inheritance Hierarchy

System.Object
   ArcGIS.Desktop.Framework.Contracts.PropertyChangedBase
      ArcGIS.Desktop.Core.Item
                  ArcGIS.Desktop.Catalog.GDBProjectItem

Requirements

Target Platforms: Windows 10, Windows 8.1, Windows 7

See Also

Reference

GDBProjectItem Members
ArcGIS.Desktop.Catalog Namespace