de.fuberlin.wiwiss.d2rq.algebra
Interface Relation

All Superinterfaces:
RelationalOperators
All Known Implementing Classes:
RelationImpl

public interface Relation
extends RelationalOperators

TODO Describe this type TODO Add uniqueConstraints() TODO Explicitly list tables

Version:
$Id: Relation.java,v 1.5 2006/09/13 14:06:23 cyganiak Exp $
Author:
Richard Cyganiak (richard@cyganiak.de)

Field Summary
static Relation EMPTY
           
static Relation TRUE
           
 
Method Summary
 AliasMap aliases()
          The tables that are used to set up this relation, both in their aliased form, and with their original physical names.
 Map attributeConditions()
          All tuples in the relation must have a certain value for an attribute if present in this map.
 Expression condition()
          An expression that must be satisfied for all tuples in the relation.
 ConnectedDB database()
           
 Set joinConditions()
          Returns the join conditions that must hold between the tables in the relation.
 
Methods inherited from interface de.fuberlin.wiwiss.d2rq.algebra.RelationalOperators
renameColumns, select
 

Field Detail

EMPTY

static final Relation EMPTY

TRUE

static final Relation TRUE
Method Detail

database

ConnectedDB database()

aliases

AliasMap aliases()
The tables that are used to set up this relation, both in their aliased form, and with their original physical names.

Returns:
All table aliases required by this relation

joinConditions

Set joinConditions()
Returns the join conditions that must hold between the tables in the relation.

Returns:
A set of Joins

condition

Expression condition()
An expression that must be satisfied for all tuples in the relation.

Returns:
An expression; Expression.TRUE indicates no condition

attributeConditions

Map attributeConditions()
All tuples in the relation must have a certain value for an attribute if present in this map.

Returns:
A map from Attributen to strings