Backport of Bug#27525 to mysql-next-mr

------------------------------------------------------------
revno: 2572.2.1
revision-id: sp1r-davi@mysql.com/endora.local-20080227225948-16317
parent: sp1r-anozdrin/alik@quad.-20080226165712-10409
committer: davi@mysql.com/endora.local
timestamp: Wed 2008-02-27 19:59:48 -0300
message:
  Bug#27525 table not found when using multi-table-deletes with aliases over several databas
  Bug#30234 Unexpected behavior using DELETE with AS and USING

  The multi-delete statement has a documented limitation that
  cross-database multiple-table deletes using aliases are not
  supported because it fails to find the tables by alias if it
  belongs to a different database. The problem is that when
  building the list of tables to delete from, if a database
  name is not specified (maybe an alias) it defaults to the
  name of the current selected database, making impossible to
  to properly resolve tables by alias later. Another problem
  is a inconsistency of the multiple table delete syntax that
  permits ambiguities in a delete statement (aliases that refer
  to multiple different tables or vice-versa).

  The first step for a solution and proper implementation of
  the cross-databse multiple table delete is to get rid of any
  ambiguities in a multiple table statement. Currently, the parser
  is accepting multiple table delete statements that have no obvious
  meaning, such as:

  DELETE a1 FROM db1.t1 AS a1, db2.t2 AS a1;
  DELETE a1 AS a1 FROM db1.t1 AS a1, db2.t2 AS a1;

  The solution is to resolve the left part of a delete statement
  using the right part, if the a table on right has an alias,
  it must be referenced in the left using the given alias. Also,
  each table on the left side must match unambiguously only one
  table in the right side.

mysql-test/r/delete.result:
  Add test case result for Bug#27525 and Bug#21148
mysql-test/r/derived.result:
  Update error.
mysql-test/suite/rpl/r/rpl_multi_delete2.result:
  Update syntax.
mysql-test/suite/rpl/t/rpl_multi_delete2.test:
  Update syntax.
mysql-test/t/delete.test:
  Add test case for Bug#27525 and Bug#21148
mysql-test/t/derived.test:
  Update statement error, alias is properly resolved now.
sql/sql_parse.cc:
  Implement new algorithm for the resolution of alias in
  a multiple table delete statement.
sql/sql_yacc.yy:
  Rework multi-delete parser rules to not accept table alias
  for the table source list.
sql/table.h:
  Add flag to signal that the table has a alias set or
  that fully qualified table name was given.

sql/sql_parse.cc

@@ -6486,13 +6486,17 @@ TABLE_LIST *st_select_lex::add_table_to_list(THD *thd,
     DBUG_RETURN(0);				/* purecov: inspected */
   if (table->db.str)
   {
+    ptr->is_fqtn= TRUE;
     ptr->db= table->db.str;
     ptr->db_length= table->db.length;
   }
   else if (lex->copy_db_to(&ptr->db, &ptr->db_length))
     DBUG_RETURN(0);
+  else
+    ptr->is_fqtn= FALSE;
 
   ptr->alias= alias_str;
+  ptr->is_alias= alias ? TRUE : FALSE;
   if (lower_case_table_names && table->table.length)
     table->table.length= my_casedn_str(files_charset_info, table->table.str);
   ptr->table_name=table->table.str;
@@ -7539,6 +7543,63 @@ bool multi_delete_precheck(THD *thd, TABLE_LIST *tables)
 }
 
 
+/*
+  Given a table in the source list, find a correspondent table in the
+  table references list.
+
+  @param lex Pointer to LEX representing multi-delete.
+  @param src Source table to match.
+  @param ref Table references list.
+
+  @remark The source table list (tables listed before the FROM clause
+  or tables listed in the FROM clause before the USING clause) may
+  contain table names or aliases that must match unambiguously one,
+  and only one, table in the target table list (table references list,
+  after FROM/USING clause).
+
+  @return Matching table, NULL otherwise.
+*/
+
+static TABLE_LIST *multi_delete_table_match(LEX *lex, TABLE_LIST *tbl,
+                                            TABLE_LIST *tables)
+{
+  TABLE_LIST *match= NULL;
+  DBUG_ENTER("multi_delete_table_match");
+
+  for (TABLE_LIST *elem= tables; elem; elem= elem->next_local)
+  {
+    int cmp;
+
+    if (tbl->is_fqtn && elem->is_alias)
+      continue; /* no match */
+    if (tbl->is_fqtn && elem->is_fqtn)
+      cmp= my_strcasecmp(table_alias_charset, tbl->table_name, elem->table_name) ||
+           strcmp(tbl->db, elem->db);
+    else if (elem->is_alias)
+      cmp= my_strcasecmp(table_alias_charset, tbl->alias, elem->alias);
+    else
+      cmp= my_strcasecmp(table_alias_charset, tbl->table_name, elem->table_name) ||
+           strcmp(tbl->db, elem->db);
+
+    if (cmp)
+      continue;
+
+    if (match)
+    {
+      my_error(ER_NONUNIQ_TABLE, MYF(0), elem->alias);
+      DBUG_RETURN(NULL);
+    }
+
+    match= elem;
+  }
+
+  if (!match)
+    my_error(ER_UNKNOWN_TABLE, MYF(0), tbl->table_name, "MULTI DELETE");
+
+  DBUG_RETURN(match);
+}
+
+
 /**
   Link tables in auxilary table list of multi-delete with corresponding
   elements in main table list, and set proper locks for them.
@@ -7564,20 +7625,9 @@ bool multi_delete_set_locks_and_link_aux_tables(LEX *lex)
   {
     lex->table_count++;
     /* All tables in aux_tables must be found in FROM PART */
-    TABLE_LIST *walk;
-    for (walk= tables; walk; walk= walk->next_local)
-    {
-      if (!my_strcasecmp(table_alias_charset,
-			 target_tbl->alias, walk->alias) &&
-	  !strcmp(walk->db, target_tbl->db))
-	break;
-    }
+    TABLE_LIST *walk= multi_delete_table_match(lex, target_tbl, tables);
     if (!walk)
-    {
-      my_error(ER_UNKNOWN_TABLE, MYF(0),
-               target_tbl->table_name, "MULTI DELETE");
       DBUG_RETURN(TRUE);
-    }
     if (!walk->derived)
     {
       target_tbl->table_name= walk->table_name;