Index: src/resolve.c
==================================================================
--- src/resolve.c
+++ src/resolve.c
@@ -95,10 +95,28 @@
   ExprSetProperty(pExpr, EP_Static);
   sqlite3ExprDelete(db, pExpr);
   memcpy(pExpr, pDup, sizeof(*pExpr));
   sqlite3DbFree(db, pDup);
 }
+
+
+/*
+** Return TRUE if the name zCol occurs anywhere in the USING clause.
+**
+** Return FALSE if the USING clause is NULL or if it does not contain
+** zCol.
+*/
+static int nameInUsingClause(IdList *pUsing, const char *zCol){
+  if( pUsing ){
+    int k;
+    for(k=0; k<pUsing->nId; k++){
+      if( sqlite3StrICmp(pUsing->a[k].zName, zCol)==0 ) return 1;
+    }
+  }
+  return 0;
+}
+
 
 /*
 ** Given the name of a column of the form X.Y.Z or Y.Z or just Z, look up
 ** that name in the set of source tables in pSrcList and make the pExpr 
 ** expression node refer back to that source column.  The following changes
@@ -187,38 +205,25 @@
           pSchema = pTab->pSchema;
           pMatch = pItem;
         }
         for(j=0, pCol=pTab->aCol; j<pTab->nCol; j++, pCol++){
           if( sqlite3StrICmp(pCol->zName, zCol)==0 ){
-            IdList *pUsing;
+            /* If there has been exactly one prior match and this match
+            ** is for the right-hand table of a NATURAL JOIN or is in a 
+            ** USING clause, then skip this match.
+            */
+            if( cnt==1 ){
+              if( pItem->jointype & JT_NATURAL ) continue;
+              if( nameInUsingClause(pItem->pUsing, zCol) ) continue;
+            }
             cnt++;
             pExpr->iTable = pItem->iCursor;
             pExpr->pTab = pTab;
             pMatch = pItem;
             pSchema = pTab->pSchema;
             /* Substitute the rowid (column -1) for the INTEGER PRIMARY KEY */
             pExpr->iColumn = j==pTab->iPKey ? -1 : (i16)j;
-            if( i<pSrcList->nSrc-1 ){
-              if( pItem[1].jointype & JT_NATURAL ){
-                /* If this match occurred in the left table of a natural join,
-                ** then skip the right table to avoid a duplicate match */
-                pItem++;
-                i++;
-              }else if( (pUsing = pItem[1].pUsing)!=0 ){
-                /* If this match occurs on a column that is in the USING clause
-                ** of a join, skip the search of the right table of the join
-                ** to avoid a duplicate match there. */
-                int k;
-                for(k=0; k<pUsing->nId; k++){
-                  if( sqlite3StrICmp(pUsing->a[k].zName, zCol)==0 ){
-                    pItem++;
-                    i++;
-                    break;
-                  }
-                }
-              }
-            }
             break;
           }
         }
       }
     }

Index: test/where3.test
==================================================================
--- test/where3.test
+++ test/where3.test
@@ -339,7 +339,90 @@
 } {
   0 0 1 {SEARCH TABLE aaa USING INDEX aaa_333 (fk=?) (~10 rows)} 
   0 1 0 {SEARCH TABLE aaa AS bbb USING INTEGER PRIMARY KEY (rowid=?) (~1 rows)} 
   0 0 0 {USE TEMP B-TREE FOR ORDER BY}
 }
+
+# Name resolution with NATURAL JOIN and USING
+#
+do_test where3-6.setup {
+  db eval {
+    CREATE TABLE t6w(a, w);
+    INSERT INTO t6w VALUES(1, 'w-one');
+    INSERT INTO t6w VALUES(2, 'w-two');
+    INSERT INTO t6w VALUES(9, 'w-nine');
+    CREATE TABLE t6x(a, x);
+    INSERT INTO t6x VALUES(1, 'x-one');
+    INSERT INTO t6x VALUES(3, 'x-three');
+    INSERT INTO t6x VALUES(9, 'x-nine');
+    CREATE TABLE t6y(a, y);
+    INSERT INTO t6y VALUES(1, 'y-one');
+    INSERT INTO t6y VALUES(4, 'y-four');
+    INSERT INTO t6y VALUES(9, 'y-nine');
+    CREATE TABLE t6z(a, z);
+    INSERT INTO t6z VALUES(1, 'z-one');
+    INSERT INTO t6z VALUES(5, 'z-five');
+    INSERT INTO t6z VALUES(9, 'z-nine');
+  }
+} {}
+set cnt 0
+foreach predicate {
+   {}
+   {ORDER BY a}
+   {ORDER BY t6w.a}
+   {WHERE a>0}
+   {WHERE t6y.a>0}
+   {WHERE a>0 ORDER BY a}
+} {
+  incr cnt
+  do_test where3-6.$cnt.1 {
+    set sql "SELECT * FROM t6w NATURAL JOIN t6x NATURAL JOIN t6y"
+    append sql " NATURAL JOIN t6z "
+    append sql $::predicate
+    db eval $sql
+  } {1 w-one x-one y-one z-one 9 w-nine x-nine y-nine z-nine}
+  do_test where3-6.$cnt.2 {
+    set sql "SELECT * FROM t6w JOIN t6x USING(a) JOIN t6y USING(a)"
+    append sql " JOIN t6z USING(a) "
+    append sql $::predicate
+    db eval $sql
+  } {1 w-one x-one y-one z-one 9 w-nine x-nine y-nine z-nine}
+  do_test where3-6.$cnt.3 {
+    set sql "SELECT * FROM t6w NATURAL JOIN t6x JOIN t6y USING(a)"
+    append sql " JOIN t6z USING(a) "
+    append sql $::predicate
+    db eval $sql
+  } {1 w-one x-one y-one z-one 9 w-nine x-nine y-nine z-nine}
+  do_test where3-6.$cnt.4 {
+    set sql "SELECT * FROM t6w JOIN t6x USING(a) NATURAL JOIN t6y"
+    append sql " JOIN t6z USING(a) "
+    append sql $::predicate
+    db eval $sql
+  } {1 w-one x-one y-one z-one 9 w-nine x-nine y-nine z-nine}
+  do_test where3-6.$cnt.5 {
+    set sql "SELECT * FROM t6w JOIN t6x USING(a) JOIN t6y USING(a)"
+    append sql " NATURAL JOIN t6z "
+    append sql $::predicate
+    db eval $sql
+  } {1 w-one x-one y-one z-one 9 w-nine x-nine y-nine z-nine}
+  do_test where3-6.$cnt.6 {
+    set sql "SELECT * FROM t6w JOIN t6x USING(a) NATURAL JOIN t6y"
+    append sql " NATURAL JOIN t6z "
+    append sql $::predicate
+    db eval $sql
+  } {1 w-one x-one y-one z-one 9 w-nine x-nine y-nine z-nine}
+  do_test where3-6.$cnt.7 {
+    set sql "SELECT * FROM t6w NATURAL JOIN t6x JOIN t6y USING(a)"
+    append sql " NATURAL JOIN t6z "
+    append sql $::predicate
+    db eval $sql
+  } {1 w-one x-one y-one z-one 9 w-nine x-nine y-nine z-nine}
+  do_test where3-6.$cnt.8 {
+    set sql "SELECT * FROM t6w NATURAL JOIN t6x NATURAL JOIN t6y"
+    append sql " JOIN t6z USING(a) "
+    append sql $::predicate
+    db eval $sql
+  } {1 w-one x-one y-one z-one 9 w-nine x-nine y-nine z-nine}
+}
+
 
 finish_test