SCRUM

DEFAULT in UPDATE and SELECT

sql/field.h

@@ -78,10 +78,11 @@ class Field
   virtual void reset_fields() {}
   virtual void set_default()
   {
-    memcpy(ptr, ptr + table->rec_buff_length, pack_length());
+    my_ptrdiff_t offset = table->default_values - table->record[0];
+    memcpy(ptr, ptr + offset, pack_length());
     if (null_ptr)
       *null_ptr= ((*null_ptr & (uchar) ~null_bit) |
-		  null_ptr[table->rec_buff_length] & null_bit);
+		  null_ptr[offset] & null_bit);
   }
   virtual bool binary() const { return 1; }
   virtual bool zero_pack() const { return 1; }

sql/item.cc

@@ -1120,6 +1120,37 @@ bool Item_ref::check_loop(uint id)
   DBUG_RETURN((*ref)->check_loop(id));
 }
 
+bool Item_default_value::eq(const Item *item, bool binary_cmp) const
+{
+  return item->type() == DEFAULT_VALUE_ITEM && 
+    ((Item_default_value *)item)->arg->eq(arg, binary_cmp);
+}
+
+bool Item_default_value::fix_fields(THD *thd, struct st_table_list *table_list, Item **items)
+{
+  bool res= arg->fix_fields(thd, table_list, items);
+  if (res)
+    return res;
+  if (arg->type() == REF_ITEM)
+  {
+    Item_ref *ref= (Item_ref *)arg;
+    if (ref->ref[0]->type() != FIELD_ITEM)
+    {
+      return 1;
+    }
+    arg= ref->ref[0];
+  }
+  Item_field *field_arg= (Item_field *)arg;
+  Field *def_field= (Field*) sql_alloc(field_arg->field->size_of());
+  if (!def_field)
+    return 1;
+  memcpy(def_field, field_arg->field, field_arg->field->size_of());
+  def_field->move_field(def_field->table->default_values - 
+			def_field->table->record[0]);
+  set_field(def_field);
+  return 0;
+}
+
 
 /*
   If item is a const function, calculate it and return a const item

sql/item.h

@@ -36,7 +36,7 @@ class Item {
 	     COPY_STR_ITEM,FIELD_AVG_ITEM, DEFAULT_ITEM,
 	     PROC_ITEM,COND_ITEM,REF_ITEM,FIELD_STD_ITEM, 
 	     FIELD_VARIANCE_ITEM,CONST_ITEM,
-             SUBSELECT_ITEM, ROW_ITEM};
+             SUBSELECT_ITEM, ROW_ITEM, DEFAULT_VALUE_ITEM};
   enum cond_result { COND_UNDEF,COND_OK,COND_TRUE,COND_FALSE };
 
   String str_value;			/* used to store value */
@@ -216,9 +216,9 @@ class Item_field :public Item_ident
   bool get_date(TIME *ltime,bool fuzzydate);  
   bool get_time(TIME *ltime);  
   bool is_null() { return field->is_null(); }
+  friend class Item_default_value;
 };
 
-
 class Item_null :public Item
 {
 public:
@@ -706,6 +706,17 @@ class Item_field_buff :public Item_buff
   bool cmp(void);
 };
 
+class Item_default_value : public Item_field
+{
+public:
+  Item *arg;
+  Item_default_value(Item *a) : 
+    Item_field((const char *)NULL, (const char *)NULL, (const char *)NULL), arg(a) {}
+  enum Type type() const { return DEFAULT_VALUE_ITEM; }
+  bool eq(const Item *item, bool binary_cmp) const;
+  bool fix_fields(THD *, struct st_table_list *, Item **);
+};
+
 extern Item_buff *new_Item_buff(Item *item);
 extern Item_result item_cmp_type(Item_result a,Item_result b);
 extern Item *resolve_const_item(Item *item,Item *cmp_item);

sql/sql_yacc.yy

@@ -2037,6 +2037,8 @@ simple_expr:
 	  { $$= new Item_func_conv_charset3($3,$7,$5); }
 	| FUNC_ARG0 '(' ')'
 	  { $$= ((Item*(*)(void))($1.symbol->create_func))();}
+	| DEFAULT '(' simple_ident ')'
+	  { $$= new Item_default_value($3); }
 	| FUNC_ARG1 '(' expr ')'
 	  { $$= ((Item*(*)(Item*))($1.symbol->create_func))($3);}
 	| FUNC_ARG2 '(' expr ',' expr ')'
@@ -3136,12 +3138,12 @@ update:
 	;
 
 update_list:
-	update_list ',' simple_ident equal expr
+	update_list ',' simple_ident equal expr_or_default
 	{
 	  if (add_item_to_list(YYTHD, $3) || add_value_to_list(YYTHD, $5))
 	    YYABORT;
 	}
-	| simple_ident equal expr
+	| simple_ident equal expr_or_default
 	  {
 	    if (add_item_to_list(YYTHD, $1) || add_value_to_list(YYTHD, $3))
 	      YYABORT;

sql/table.cc

@@ -260,6 +260,8 @@ int openfrm(const char *name, const char *alias, uint db_stat, uint prgflag,
     if (db_stat & HA_READ_ONLY)
       outparam->record[1]=outparam->record[0]; /* purecov: inspected */
   }
+  
+  outparam->default_values= outparam->record[2];
 
   VOID(my_seek(file,pos,MY_SEEK_SET,MYF(0)));
   if (my_read(file,(byte*) head,288,MYF(MY_NABP))) goto err_not_open;

sql/table.h

@@ -54,6 +54,7 @@ struct st_table {
   Field_blob **blob_field;		/* Pointer to blob fields */
   HASH	name_hash;			/* hash of field names */
   byte *record[3];			/* Pointer to records */
+  byte *default_values;
   uint fields;				/* field count */
   uint reclength;			/* Recordlength */
   uint rec_buff_length;