--- a/src/main/scala/RDB2RDFMain.scala	Thu Jan 07 19:18:56 2010 -0500
+++ b/src/main/scala/RDB2RDFMain.scala	Thu Jan 07 19:20:54 2010 -0500
@@ -64,15 +64,22 @@
   }
 
   def uriConstraint(state:R2RState, constrainMe:sql.RelAliasAttribute, u:sparql.ObjUri, enforeForeignKeys:Boolean):R2RState = {
-    // println("equiv+= " + toString(constrainMe) + "=" + value)
-    //R2RState(state.joins, state.varmap, state.exprs + RelationalExpressionEq(constrainMe,PrimaryExpressionTyped(SQLDatatype.INTEGER,Name(u.v.s))))
-    val relvar = if (enforeForeignKeys) sql.RelAliasAttribute(constrainMe.relalias, sql.Attribute(sql.Name(u.attr.s))) else constrainMe
-    R2RState(state.joins, state.varmap, state.exprs + sql.RelationalExpressionEq(sql.PrimaryExpressionAttr(relvar),sql.PrimaryExpressionTyped(sql.Datatype.INTEGER,sql.Name(u.v.s))))
+    val relvar =
+      if (enforeForeignKeys)
+	sql.RelAliasAttribute(constrainMe.relalias, sql.Attribute(sql.Name(u.attr.s)))
+      else
+	constrainMe
+    R2RState(state.joins,
+	     state.varmap,
+	     state.exprs + sql.RelationalExpressionEq(sql.PrimaryExpressionAttr(relvar),
+						      sql.PrimaryExpressionTyped(sql.Datatype.INTEGER,sql.Name(u.v.s))))
   }
 
   def literalConstraint(state:R2RState, constrainMe:sql.RelAliasAttribute, lit:sparql.Literal, dt:sql.Datatype):R2RState = {
-    // println("equiv+= " + toString(attr) + "=" + lit)
-    R2RState(state.joins, state.varmap, state.exprs + sql.RelationalExpressionEq(sql.PrimaryExpressionAttr(constrainMe),sql.PrimaryExpressionTyped(dt,sql.Name(lit.lit.lexicalForm))))    
+    R2RState(state.joins,
+	     state.varmap,
+	     state.exprs + sql.RelationalExpressionEq(sql.PrimaryExpressionAttr(constrainMe),
+						      sql.PrimaryExpressionTyped(dt,sql.Name(lit.lit.lexicalForm))))    
   }
 
   /** varConstraint
@@ -96,7 +103,8 @@
     if (state.varmap.contains(v) && varToAttribute(state.varmap, v) != constrainMe) {
       /* The variable has already been bound to another attribute. */
       /* Constraint against the initial binding for this variable. */
-      val constraint = sql.RelationalExpressionEq(sql.PrimaryExpressionAttr(varToAttribute(state.varmap, v)), sql.PrimaryExpressionAttr(constrainMe))
+      val constraint = sql.RelationalExpressionEq(sql.PrimaryExpressionAttr(constrainMe),
+						  sql.PrimaryExpressionAttr(varToAttribute(state.varmap, v)))
       R2RState(state.joins, state.varmap, 
 	       if (varToAttributeDisjoints(state.varmap, v).size > 0) {
 		 state.exprs ++ {varToAttributeDisjoints(state.varmap, v) map ((d) => sql.ExprDisjunction(Set(d, constraint)))}
@@ -164,8 +172,16 @@
 	}
 	val state_subjJoin = R2RState(state_postSubj.joins + sql.InnerJoin(sql.AliasedResource(rel,relalias)), state_postSubj.varmap, state_postSubj.exprs)
 
+	try { db.relationdescs(rel).attributes(attr) } catch {
+	  case e:java.util.NoSuchElementException =>
+	    throw new Exception("error processing { " + s + " " + p + " " + o + " } :db.relationdescs(" + rel + ").attributes(" + attr + ") not found in " + db)
+	}
 	val (targetattr, targetrel, dt, state_fkeys:R2RState) = db.relationdescs(rel).attributes(attr) match {
 	  case sql.ForeignKey(fkrel, fkattr) => {
+	    try { db.relationdescs(fkrel).attributes(fkattr) } catch {
+	      case e:java.util.NoSuchElementException =>
+		throw new Exception("db.relationdescs(" + fkrel + ").attributes(" + fkattr + ") not found in " + db)
+	    }
 	    val fkdt = db.relationdescs(fkrel).attributes(fkattr) match {
 	      case sql.ForeignKey(dfkrel, dfkattr) => error("foreign key " + rel.n + "." + attr.n + 
 							"->" + fkrel.n + "." + fkattr.n + 
@@ -177,7 +193,8 @@
 	      val fkaliasattr = sql.RelAliasAttribute(oRelAlias, fkattr)
 	      val state_t = R2RState(state_subjJoin.joins + sql.InnerJoin(sql.AliasedResource(fkrel,oRelAlias)),
 				     state_subjJoin.varmap,
-				     state_subjJoin.exprs + sql.RelationalExpressionEq(sql.PrimaryExpressionAttr(fkaliasattr),sql.PrimaryExpressionAttr(objattr)))
+				     state_subjJoin.exprs + sql.RelationalExpressionEq(sql.PrimaryExpressionAttr(fkaliasattr),
+										       sql.PrimaryExpressionAttr(objattr)))
 
 	      (fkaliasattr, fkrel, fkdt, state_t)
 	    } else {
@@ -402,8 +419,8 @@
 	      val newConstraints =
 		if (varToAttribute(outerState.varmap, v) != varAliasAttr) {
 		  /* Constraint against binding from earlier GP. */
-		  val constraint = sql.RelationalExpressionEq(sql.PrimaryExpressionAttr(varToAttribute(outerState.varmap, v)),
-							      sql.PrimaryExpressionAttr(varAliasAttr))
+		  val constraint = sql.RelationalExpressionEq(sql.PrimaryExpressionAttr(varAliasAttr),
+							      sql.PrimaryExpressionAttr(varToAttribute(outerState.varmap, v)))
 		  if (varToAttributeDisjoints(outerState.varmap, v).size > 0)
 		    // (union0._DISJOINT_ != 0 OR union0.x=union1.x) AND (union1._DISJOINT_ != 2 OR union0.x=union1.x)
 		    varToAttributeDisjoints(outerState.varmap, v) map ((d) =>
@@ -508,8 +525,8 @@
 	      Map()
 	    val newConstraints = {
 	      /* Constraint against binding from earlier GP. */
-	      val constraint = sql.RelationalExpressionEq(sql.PrimaryExpressionAttr(varToAttribute(state_postLeadingTable.varmap, v)),
-							  sql.PrimaryExpressionAttr(varAliasAttr))
+	      val constraint = sql.RelationalExpressionEq(sql.PrimaryExpressionAttr(varAliasAttr),
+							  sql.PrimaryExpressionAttr(varToAttribute(state_postLeadingTable.varmap, v)))
 	      if (varToAttributeDisjoints(state_postLeadingTable.varmap, v).size > 0)
 		// (leftJoin0._DISJOINT_ IS NOT NULL AND leftJoin1._DISJOINT_ IS NOT NULL) OR leftJoin0.x=leftJoin1.x
 		varToAttributeDisjoints(state_postLeadingTable.varmap, v) map ((d) => sql.ExprDisjunction(Set(d, constraint)))