ArcObjects Library Reference (GeoDatabase)

IQueryName2 Interface

Provides access to the associated query definition.

Product Availability

Available with ArcGIS Engine, ArcGIS Desktop, and ArcGIS Server.

Members

		Description
	CopyLocally	Indicates if the data must be copied locally.
	PrimaryKey	The primary key field names.
	QueryDef	QueryDef of feature class name.

Inherited Interfaces

Interfaces	Description
IQueryName	Provides access to the associated query definition.

CoClasses that implement IQueryName2

CoClasses and Classes	Description
FeatureQueryName	Esri Feature Query Name object.
TableQueryName	Esri Table Query Name object.

Remarks

This interface extends the IQueryName interface to allow Objects in tables created from a QueryDef. The table used in the QueryDef does not need to be registered with the geodatabase in order for the table generated from the QueryDef to have Object ID's. An Object ID column is required for a table to support selections. If the QueryDef includes a geometry column, a FeatureClass is created when the name object is opened.

How the PrimaryKey and CopyLocally properties are set determines whether or not the table will have an Object ID column. The following describes the various scenarios:

If the PrimaryKey property is set, the field or fields indicated will be used to generate Object ID's regardless of how CopyLocally is set.
If a column in the QueryDef is an Object ID column, this will be used as the PrimaryKey if the QueryDef involves a single table. The Object ID is used even if the PrimaryKey is set to another column. This happens regardless of how the CopyLocally property is set.
In all other cases, the CopyLocally property is used to determine the course of action. If CopyLocally is True, then the rows returned from the QueryDef are copied to a local file and assigned an Object ID values. If CopyLocally is False, the data is accessed directly from the database and the rows will not have Object ID's.

[C#]

There are three ways in which Object ID's are assigned to a table:

Direct - The values from the primary key field are used directly as Object ID's. Here the primary key must be a single field and of integer type.

    public void IQueryName2_Direct(IWorkspace workspace)
    {
        IFeatureWorkspace featureWorkspace = (IFeatureWorkspace)workspace;
        IQueryDef queryDef = featureWorkspace.CreateQueryDef();
        queryDef.SubFields = "*";
        queryDef.Tables = "parcels, house_listings";
        queryDef.WhereClause = "parcel.parcel_id = house_listing.parcel_id";

        //Direct
        IQueryName2 queryName2 = new TableQueryNameClass();
        queryName2.PrimaryKey = "parcel.parcel_id";
        queryName2.QueryDef = queryDef;
    }

Wrapped - The primary key values are mapped to unique integer values which are used as the Object ID's. The primary key in this case is set to a list of fields (i.e. composite keys) or a single non-integer field. Two mapping tables are created in memory (Object ID-> PrimaryKey, PrimaryKey-> Object ID). If the tables are too large to fit in memory, virtual memory will be used.

    public void IQueryName2_Wrapped(IWorkspace workspace)
    {
        IFeatureWorkspace featureWorkspace = (IFeatureWorkspace)workspace;
        IQueryDef queryDef = featureWorkspace.CreateQueryDef();
        queryDef.SubFields = "*";
        queryDef.Tables = "parcels, house_listings";
        queryDef.WhereClause = "parcel.parcel_id = house_listing.parcel_id";

        //Wrapped
        IQueryName2 queryName2 = new TableQueryNameClass();
        queryName2.PrimaryKey = "parcel.rout_id, parcel.parcel_id";
        queryName2.QueryDef = queryDef;
    }

Copy - No primary key is set and CopyLocally is set to True. In this case, the table is copied into the scratch workspace and an Object ID field is appended. The scratch workspace is usually under your system temp directory in a file named mx<n>.mdb.

    public void IQueryName2_Copy(IWorkspace workspace)
    {
        IFeatureWorkspace featureWorkspace = (IFeatureWorkspace)workspace;
        IQueryDef queryDef = featureWorkspace.CreateQueryDef();
        queryDef.SubFields = "*";
        queryDef.Tables = "parcels, house_listings";
        queryDef.WhereClause = "parcel.parcel_id = house_listing.parcel_id";

        //Copy
        IQueryName2 queryName2 = new TableQueryNameClass();
        queryName2.PrimaryKey = "";
        queryName2.CopyLocally = true;
        queryName2.QueryDef = queryDef;
    }

With copy tables, the fields are renamed (A.field1-> A_field1), but the qualified name is still the alias name.
If you are working with feature classes use FeatureQueryName rather than TableQueryName.

The following diagram illustrates how the criteria described above is used to generate tables from TableQueryNames and FeatureQueryNames:

[C++]

[Visual Basic .NET]

There are three ways in which Object ID's are assigned to a table:

Direct - The values from the primary key field are used directly as Object ID's. Here the primary key must be a single field and of integer type.

Wrapped - The primary key values are mapped to unique integer values which are used as the Object ID's. The primary key in this case is set to a list of fields (i.e. composite keys) or a single non-integer field. Two mapping tables are created in memory (Object ID-> PrimaryKey, PrimaryKey-> Object ID). If the tables are too large to fit in memory, virtual memory will be used.

Copy - No primary key is set and CopyLocally is set to True. In this case, the table is copied into the scratch workspace and an Object ID field is appended. The scratch workspace is usually under your system temp directory in a file named mx<n>.mdb.

With copy tables, the fields are renamed (A.field1-> A_field1), but the qualified name is still the alias name.

If you are working with feature classes use FeatureQueryName rather than TableQueryName.

The following diagram illustrates how the criteria described above is used to generate tables from TableQueryNames and FeatureQueryNames:

.NET Related Topics

Joining data | Querying geodatabase tables