MDEV-23519 Protocol packet - "Original Name" info is showing alias name,

instead of original name of the column

When doing refactoring of temporary table field creation a mistake was
done when copying the column name when creating internal temporary tables.
For internal temporary tables we should use the original field name, not
the item name (= alias).

client/mysql.cc

@@ -3503,6 +3503,7 @@ print_field_types(MYSQL_RES *result)
   while ((field = mysql_fetch_field(result)))
   {
     tee_fprintf(PAGER, "Field %3u:  `%s`\n"
+                       "Org_field:  `%s`\n"
                        "Catalog:    `%s`\n"
                        "Database:   `%s`\n"
                        "Table:      `%s`\n"
@@ -3514,8 +3515,8 @@ print_field_types(MYSQL_RES *result)
                        "Decimals:   %u\n"
                        "Flags:      %s\n\n",
                 ++i,
-                field->name, field->catalog, field->db, field->table,
-                field->org_table, fieldtype2str(field->type),
+                field->name, field->org_name, field->catalog, field->db,
+                field->table, field->org_table, fieldtype2str(field->type),
                 get_charset_name(field->charsetnr), field->charsetnr,
                 field->length, field->max_length, field->decimals,
                 fieldflags2str(field->flags));

mysql-test/main/alias.result

@@ -218,3 +218,22 @@ DELETE ZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZ
 ERROR 42000: You have an error in your SQL syntax; check the manual that corresponds to your MariaDB server version for the right syntax to use near 't1 WHERE 1=1' at line 1
 connection default;
 disconnect c1;
+#
+# MDEV-23519
+#
+create or replace table t1 (a int);
+create or replace table t2 (b int);
+insert into t1 values(1),(2);
+insert into t2 values(1),(2);
+select t1.a as a1 from t1 as t1,t2 order by t2.b,t1.a;
+Catalog	Database	Table	Table_alias	Column	Column_alias	Type	Length	Max length	Is_null	Flags	Decimals	Charsetnr
+def	test	t1	t1	a	a1	3	11	1	Y	32768	0	63
+a1
+1
+2
+1
+2
+drop table t1,t2;
+#
+# End of 10.4 tests
+#

sql/sql_select.cc

@@ -17972,7 +17972,14 @@ Field *Item::create_field_for_schema(THD *thd, TABLE *table)
 /**
   Create a temporary field for Item_field (or its descendant),
   either direct or referenced by an Item_ref.
+
+  param->modify_item is set when we create a field for an internal temporary
+  table. In this case we have to ensure the new field name is identical to
+  the original field name as the field will info will be sent to the client.
+  In other cases, the field name is set from orig_item or name if org_item is
+  not set.
 */
+
 Field *
 Item_field::create_tmp_field_from_item_field(TABLE *new_table,
                                              Item_ref *orig_item,
@@ -17980,6 +17987,10 @@ Item_field::create_tmp_field_from_item_field(TABLE *new_table,
 {
   DBUG_ASSERT(!is_result_field());
   Field *result;
+  LEX_CSTRING *new_name= (orig_item ? &orig_item->name :
+                          !param->modify_item() ? &name :
+                          &field->field_name);
+
   /*
     If item have to be able to store NULLs but underlaid field can't do it,
     create_tmp_field_from_field() can't be used for tmp field creation.
@@ -17998,26 +18009,25 @@ Item_field::create_tmp_field_from_item_field(TABLE *new_table,
     Record_addr rec(orig_item ? orig_item->maybe_null : maybe_null);
     const Type_handler *handler= type_handler()->
                                    type_handler_for_tmp_table(this);
-    result= handler->make_and_init_table_field(orig_item ? &orig_item->name : &name,
+    result= handler->make_and_init_table_field(new_name,
                                                rec, *this, new_table);
   }
   else if (param->table_cant_handle_bit_fields() &&
            field->type() == MYSQL_TYPE_BIT)
   {
     const Type_handler *handler= type_handler_long_or_longlong();
-    result= handler->make_and_init_table_field(&name,
+    result= handler->make_and_init_table_field(new_name,
                                                Record_addr(maybe_null),
                                                *this, new_table);
   }
   else
   {
-    LEX_CSTRING *tmp= orig_item ? &orig_item->name : &name;
     bool tmp_maybe_null= param->modify_item() ? maybe_null :
                                                 field->maybe_null();
     result= field->create_tmp_field(new_table->in_use->mem_root, new_table,
                                     tmp_maybe_null);
-    if (result)
-      result->field_name= *tmp;
+    if (result && ! param->modify_item())
+      result->field_name= *new_name;
   }
   if (result && param->modify_item())
     result_field= result;