range.test:

  Added tests for != predicate.
sql_select.cc:
  Fixing bugs in Item_equal code:
  added a parameter in substitute_for_equal_field;
  modified eliminate_item_equal.
sql_list.h:
  Cleanup

mysql-test/t/range.test

@@ -323,8 +323,12 @@ insert into t2(id, uid, name) select id, uid, name from t1;
 select count(*) from t1;  
 select count(*) from t2;
 
+analyze table t1,t2;
+
 explain select * from t1, t2  where t1.uid=t2.uid AND t1.uid > 0;
+explain select * from t1, t2  where t1.uid=t2.uid AND t2.uid > 0;
 explain select * from t1, t2  where t1.uid=t2.uid AND t1.uid != 0;
+explain select * from t1, t2  where t1.uid=t2.uid AND t2.uid != 0;
 
 select * from t1, t2  where t1.uid=t2.uid AND t1.uid > 0;
 select * from t1, t2  where t1.uid=t2.uid AND t1.uid != 0;

sql/sql_list.h

@@ -271,8 +271,8 @@ public:
   inline T* head() {return (T*) base_list::head(); }
   inline T** head_ref() {return (T**) base_list::head_ref(); }
   inline T* pop()  {return (T*) base_list::pop(); }
-  inline void concat(List<T> *list) { return base_list::concat(list); }
-  inline void disjoin(List<T> *list) { return base_list::disjoin(list); }
+  inline void concat(List<T> *list) { base_list::concat(list); }
+  inline void disjoin(List<T> *list) { base_list::disjoin(list); }
   void delete_elements(void)
   {
     list_node *element,*next;
@@ -283,7 +283,6 @@ public:
     }
     empty();
   }
-  inline void concat(List<T> *list) { base_list::concat(list); }
 };
 
 

sql/sql_select.cc

@@ -77,6 +77,7 @@ static Item *flatten_condition(COND *cond);
 static COND *build_all_equal_items(COND *cond,
                                         COND_EQUAL *inherited);
 static COND* substitute_for_best_equal_field(COND *cond,
+                                             COND_EQUAL *cond_equal,
                                              void *table_join_idx);
 static COND *optimize_cond(COND *conds,Item::cond_result *cond_value);
 static COND *remove_eq_conds(COND *cond,Item::cond_result *cond_value);
@@ -690,7 +691,7 @@ JOIN::optimize()
   */
   if (conds)
   {
-    conds= substitute_for_best_equal_field(conds, map2table);
+    conds= substitute_for_best_equal_field(conds, cond_equal, map2table);
     conds->update_used_tables();
   }
   {
@@ -700,6 +701,7 @@ JOIN::optimize()
       if (tables->on_expr)
       {
         tables->on_expr= substitute_for_best_equal_field(tables->on_expr,
+                                                         cond_equal,
                                                          map2table);
         tables->on_expr->update_used_tables();
         map2table[tables->table->tablenr]->on_expr= tables->on_expr;
@@ -4703,11 +4705,8 @@ static Item *eliminate_item_equal(COND *cond, COND_EQUAL *cond_equal,
     Item_field *item= item_field;
     if (upper)
     { 
-      if (item_const)
-      {
-        if (upper->get_const())
-          item= 0;
-      }
+      if (item_const && upper->get_const())
+        item= 0;
       else
       {
         Item_equal_iterator li(*item_equal);
@@ -4745,6 +4744,7 @@ static Item *eliminate_item_equal(COND *cond, COND_EQUAL *cond_equal,
   SYNOPSIS
     substitute_for_best_equal_field()
     cond            condition to process
+    cond_equal      multiple equalities to take into consideration
     table_join_idx  index to tables determining field preference
 
   DESCRIPTION
@@ -4770,6 +4770,7 @@ static Item *eliminate_item_equal(COND *cond, COND_EQUAL *cond_equal,
 */
 
 static COND* substitute_for_best_equal_field(COND *cond,
+                                             COND_EQUAL *cond_equal,
                                              void *table_join_idx)
 {
   Item_equal *item_equal;
@@ -4777,7 +4778,6 @@ static COND* substitute_for_best_equal_field(COND *cond,
   if (cond->type() == Item::COND_ITEM)
   {
     List<Item> *cond_list= ((Item_cond*) cond)->argument_list();
-    COND_EQUAL *cond_equal= 0;
 
     bool and_level= ((Item_cond*) cond)->functype() ==
                       Item_func::COND_AND_FUNC;
@@ -4797,7 +4797,7 @@ static COND* substitute_for_best_equal_field(COND *cond,
     Item *item;
     while ((item= li++))
     {
-      Item *new_item =substitute_for_best_equal_field(item,
+      Item *new_item =substitute_for_best_equal_field(item, cond_equal,
                                                         table_join_idx);
       if (new_item != item)
         li.replace(new_item);
@@ -4817,7 +4817,9 @@ static COND* substitute_for_best_equal_field(COND *cond,
   {
     item_equal= (Item_equal *) cond;
     item_equal->sort(table_join_idx);
-    return eliminate_item_equal(0, 0, item_equal);
+    if (cond_equal && cond_equal->current_level.head() == item_equal)
+      cond_equal= 0;
+    return eliminate_item_equal(0, cond_equal, item_equal);
   }
   else
     cond->walk(&Item::replace_equal_field_processor, 0);