fix for the 2361 bug: ALTER TABLE ... DROP PRIMARY KEY drops a non-primary key

"PRIMARY" has been replaced by primary_key_name.


sql/mysql_priv.h:
  "PRIMARY" replaced by primary_key_name.
sql/sql_help.cc:
  "PRIMARY" replaced by primary_key_name.
sql/sql_select.cc:
  "PRIMARY" replaced by primary_key_name.
sql/sql_show.cc:
  "PRIMARY" replaced by primary_key_name.
sql/sql_table.cc:
  fix for the 2361 bug: ALTER TABLE ... DROP PRIMARY KEY drops a non-primary key
  "PRIMARY" replaced by primary_key_name.
sql/table.cc:
  "PRIMARY" replaced by primary_key_name.

sql/mysql_priv.h

@@ -38,6 +38,7 @@ typedef ulong key_part_map;           /* Used for finding key parts */
 /* useful constants */
 extern const key_map key_map_empty;
 extern const key_map key_map_full;
+extern const char *primary_key_name;
 
 #include "mysql_com.h"
 #include <violite.h>

sql/sql_help.cc

@@ -274,9 +274,9 @@ int get_topics_for_keyword(THD *thd, TABLE *topics, TABLE *relations,
 
   DBUG_ENTER("get_topics_for_keyword");
   
-  if ((iindex_topic= find_type((char*) "PRIMARY",
+  if ((iindex_topic= find_type((char*) primary_key_name,
 			       &topics->keynames, 1+2)-1)<0 ||
-      (iindex_relations= find_type((char*) "PRIMARY",
+      (iindex_relations= find_type((char*) primary_key_name,
 				   &relations->keynames, 1+2)-1)<0)
   {
     send_error(thd,ER_CORRUPT_HELP_DB);

sql/sql_select.cc

@@ -9130,16 +9130,16 @@ int mysql_explain_union(THD *thd, SELECT_LEX_UNIT *unit, select_result *result)
   {
     res= mysql_explain_select(thd, sl,
 			      (((&thd->lex->select_lex)==sl)?
-			       ((thd->lex->all_selects_list != sl)?"PRIMARY":
-				"SIMPLE"):
+			       ((thd->lex->all_selects_list != sl) ? 
+				primary_key_name : "SIMPLE"):
 			       ((sl == first)?
 				((sl->linkage == DERIVED_TABLE_TYPE) ?
 				 "DERIVED":
-				((sl->uncacheable & UNCACHEABLE_DEPENDENT)?
+				((sl->uncacheable & UNCACHEABLE_DEPENDENT) ?
 				 "DEPENDENT SUBQUERY":
 				 (sl->uncacheable?"UNCACHEABLE SUBQUERY":
 				   "SUBQUERY"))):
-				((sl->uncacheable & UNCACHEABLE_DEPENDENT)?
+				((sl->uncacheable & UNCACHEABLE_DEPENDENT) ?
 				 "DEPENDENT UNION":
 				 sl->uncacheable?"UNCACHEABLE UNION":
 				  "UNION"))),

sql/sql_show.cc

@@ -1167,7 +1167,7 @@ store_create_info(THD *thd, TABLE *table, String *packet)
     bool found_primary=0;
     packet->append(",\n  ", 4);
 
-    if (i == primary_key && !strcmp(key_info->name,"PRIMARY"))
+    if (i == primary_key && !strcmp(key_info->name, primary_key_name))
     {
       found_primary=1;
       packet->append("PRIMARY ", 8);

sql/sql_table.cc

@@ -29,7 +29,7 @@
 #include <io.h>
 #endif
 
-static const char *primary_key_name="PRIMARY";
+const char *primary_key_name= "PRIMARY";
 
 static bool check_if_keyname_exists(const char *name,KEY *start, KEY *end);
 static char *make_unique_key_name(const char *field_name,KEY *start,KEY *end);
@@ -2244,8 +2244,8 @@ int mysql_alter_table(THD *thd,char *new_db, char *new_name,
   {
     char *key_name= key_info->name;
 
-    if (drop_primary && !my_strcasecmp(system_charset_info, key_name,
-                                       "PRIMARY"))
+    if (drop_primary && (key_info-> flags & HA_NOSAME) &&
+	!my_strcasecmp(system_charset_info, key_name, primary_key_name))
     {
       drop_primary= 0;
       continue;
@@ -2305,7 +2305,7 @@ int mysql_alter_table(THD *thd,char *new_db, char *new_name,
       key_list.push_back(new Key(key_info->flags & HA_SPATIAL ? Key::SPATIAL :
                                  (key_info->flags & HA_NOSAME ?
 				 (!my_strcasecmp(system_charset_info,
-                                                 key_name, "PRIMARY") ?
+                                                 key_name, primary_key_name) ?
 				  Key::PRIMARY  : Key::UNIQUE) :
 				  (key_info->flags & HA_FULLTEXT ?
 				   Key::FULLTEXT : Key::MULTIPLE)),

sql/table.cc

@@ -481,8 +481,8 @@ int openfrm(const char *name, const char *alias, uint db_stat, uint prgflag,
   /* Fix key->name and key_part->field */
   if (key_parts)
   {
-    uint primary_key=(uint) (find_type((char*) "PRIMARY",&outparam->keynames,
-				       3)-1);
+    uint primary_key=(uint) (find_type((char*) primary_key_name,
+				       &outparam->keynames, 3) - 1);
     uint ha_option=outparam->file->table_flags();
     keyinfo=outparam->key_info;
     key_part=keyinfo->key_part;