ArcGIS Pro 3.1 API Reference Guide
ArcGIS.Core.Data Namespace / Join Class / Join Constructor
The JoinDescription which describes the details of the join.
Example

In This Topic
    Join Constructor
    In This Topic
    Initializes a new instance of the Join class, which represents the join of a Table or FeatureClass with another Table or FeatureClass from the same or different Datastore.
    Syntax

    Parameters

    joinDescription
    The JoinDescription which describes the details of the join.
    Exceptions
    ExceptionDescription
    joinDescription is null.
    A geodatabase-related exception has occurred.
    This object must be created within the lambda or delegate passed to QueuedTask.Run, or on a compatible STA thread.
    Example
    Joining a file geodatabase feature class to an Oracle database query layer feature class with a virtual relationship class
    public async Task JoiningFileGeodatabaseFeatureClassToOracleQueryLayer()
    {
      await ArcGIS.Desktop.Framework.Threading.Tasks.QueuedTask.Run(() =>
      {
        using (Geodatabase geodatabase = new Geodatabase(new FileGeodatabaseConnectionPath(new Uri("C:\\Data\\LocalGovernment.gdb"))))
        using (Database database = new Database(new DatabaseConnectionProperties(EnterpriseDatabaseType.Oracle)
          {
            AuthenticationMode = AuthenticationMode.DBMS,
            Instance = "instance",
            User = "user",
            Password = "password",
            Database = "database"
          }))
    
        using (FeatureClass leftFeatureClass = geodatabase.OpenDataset<FeatureClass>("Hospital"))
        using (Table rightTable = database.OpenTable(database.GetQueryDescription("FacilitySite")))
        {
          Field originPrimaryKey = leftFeatureClass.GetDefinition().GetFields().FirstOrDefault(field => field.Name.Equals("facilityId"));
          Field destinationForeignKey = rightTable.GetDefinition().GetFields().FirstOrDefault(field => field.Name.Equals("hospitalID"));
    
          VirtualRelationshipClassDescription description = new VirtualRelationshipClassDescription(
            originPrimaryKey, destinationForeignKey, RelationshipCardinality.OneToOne);
    
          using (RelationshipClass relationshipClass = leftFeatureClass.RelateTo(rightTable, description))
          {
            JoinDescription joinDescription = new JoinDescription(relationshipClass)
            {
              JoinDirection = JoinDirection.Forward,
              JoinType = JoinType.LeftOuterJoin
            };
    
            Join join = new Join(joinDescription);
    
            using (Table joinedTable = join.GetJoinedTable())
            {
              // Perform operation on joined table.
            }
          }
        }
      });
    }
    Joining two tables from different geodatabases
    public async Task JoinTablesFromDifferentGeodatabases()
    {
      await ArcGIS.Desktop.Framework.Threading.Tasks.QueuedTask.Run(() =>
      {
        using (Geodatabase sourceGeodatabase = new Geodatabase(new FileGeodatabaseConnectionPath(new Uri("Path \\ to \\Geodatabase \\ one"))))
        using (Geodatabase destinationGeodatabase = new Geodatabase(new FileGeodatabaseConnectionPath(new Uri("Path \\ to \\Geodatabase \\ two"))))
        using (Table sourceTable = sourceGeodatabase.OpenDataset<Table>("State"))
        using (Table destinationTable = destinationGeodatabase.OpenDataset<Table>("Cities"))
        {
          Field primaryKeyField = sourceTable.GetDefinition().GetFields().FirstOrDefault(field => field.Name.Equals("State.State_Abbreviation"));
          Field foreignKeyField = destinationTable.GetDefinition().GetFields().FirstOrDefault(field => field.Name.Equals("Cities.State"));
    
          VirtualRelationshipClassDescription virtualRelationshipClassDescription = new VirtualRelationshipClassDescription(primaryKeyField, foreignKeyField, RelationshipCardinality.OneToMany);
    
          using (RelationshipClass relationshipClass = sourceTable.RelateTo(destinationTable, virtualRelationshipClassDescription))
          {
            JoinDescription joinDescription = new JoinDescription(relationshipClass)
            {
              JoinDirection = JoinDirection.Forward,
              JoinType = JoinType.InnerJoin,
              TargetFields = sourceTable.GetDefinition().GetFields()
            };
    
            using (Join join = new Join(joinDescription))
            {
              Table joinedTable = join.GetJoinedTable();
    
              //Process the joined table. For example ..
              using (RowCursor cursor = joinedTable.Search())
              {
                while (cursor.MoveNext())
                {
                  using (Row row = cursor.Current)
                  {
                    // Use Row
                  }
                }
              }
            }
          }
        }
      });
    }
    Requirements

    Target Platforms: Windows 11, Windows 10

    ArcGIS Pro version: 3.0 or higher.
    See Also