Index: src/where.c
==================================================================
--- src/where.c
+++ src/where.c
@@ -2458,11 +2458,11 @@
     }else if( eOp & (WO_EQ|WO_IS) ){
       int iCol = pProbe->aiColumn[saved_nEq];
       pNew->wsFlags |= WHERE_COLUMN_EQ;
       assert( saved_nEq==pNew->u.btree.nEq );
       if( iCol==XN_ROWID 
-       || (iCol>0 && nInMul==0 && saved_nEq==pProbe->nKeyCol-1)
+       || (iCol>=0 && nInMul==0 && saved_nEq==pProbe->nKeyCol-1)
       ){
         if( iCol>=0 && pProbe->uniqNotNull==0 ){
           pNew->wsFlags |= WHERE_UNQ_WANTED;
         }else{
           pNew->wsFlags |= WHERE_ONEROW;

Index: test/join2.test
==================================================================
--- test/join2.test
+++ test/join2.test
@@ -89,7 +89,38 @@
   SELECT * FROM aa LEFT JOIN cc ON (a=b) JOIN bb ON (b=c);
 } {1 {ON clause references tables to its right}}
 do_catchsql_test 2.2 {
   SELECT * FROM aa JOIN cc ON (a=b) JOIN bb ON (b=c);
 } {0 {one one one}}
+
+#-------------------------------------------------------------------------
+# Test that a problem causing where.c to overlook opportunities to
+# omit unnecessary tables from a LEFT JOIN when UNIQUE, NOT NULL column 
+# that makes this possible happens to be the leftmost in its table.
+#
+reset_db
+do_execsql_test 3.0 {
+  CREATE TABLE t1(k1 INTEGER PRIMARY KEY, k2, k3);
+  CREATE TABLE t2(k2 INTEGER PRIMARY KEY, v2);
+
+  -- Prior to this problem being fixed, table t3_2 would be omitted from
+  -- the join queries below, but if t3_1 were used in its place it would
+  -- not.
+  CREATE TABLE t3_1(k3 PRIMARY KEY, v3) WITHOUT ROWID;
+  CREATE TABLE t3_2(v3, k3 PRIMARY KEY) WITHOUT ROWID;
+}
+
+do_eqp_test 3.1 {
+  SELECT v2 FROM t1 LEFT JOIN t2 USING (k2) LEFT JOIN t3_1 USING (k3);
+} {
+  0 0 0 {SCAN TABLE t1} 
+  0 1 1 {SEARCH TABLE t2 USING INTEGER PRIMARY KEY (rowid=?)}
+}
+
+do_eqp_test 3.2 {
+  SELECT v2 FROM t1 LEFT JOIN t2 USING (k2) LEFT JOIN t3_2 USING (k3);
+} {
+  0 0 0 {SCAN TABLE t1} 
+  0 1 1 {SEARCH TABLE t2 USING INTEGER PRIMARY KEY (rowid=?)}
+}
 
 finish_test