Bug #20191: getTableName gives wrong or inconsistent result when using VIEWs

When compiling GROUP BY Item_ref instances are dereferenced in 
setup_copy_fields(), i.e. replaced with the corresponding Item_field 
(if they point to one) or Item_copy_string for the other cases.
Since the Item_ref (in the Item_field case) is no longer used the information
about the aliases stored in it is lost.   
Fixed by preserving the column, table and DB alias on dereferencing Item_ref


mysql-test/r/metadata.result:
  Bug #20191: getTableName gives wrong or inconsistent result when using VIEWs
   - test case
mysql-test/t/metadata.test:
  Bug #20191: getTableName gives wrong or inconsistent result when using VIEWs
   - test case
sql/item.cc:
  Bug #20191: getTableName gives wrong or inconsistent result when using VIEWs
   - use the table and db name to fill up the metadata for columns
sql/sql_select.cc:
  Bug #20191: getTableName gives wrong or inconsistent result when using VIEWs
   - preserve the field, table and DB name on dereferencing an Item_ref

1 files changed, 4 insertions, 0 deletions

diff --git a/sql/item.cc b/sql/item.cc
index dc92edd651d..76f0332b4ab 100644
--- a/sql/item.cc
+++ b/sql/item.cc
@@ -4202,6 +4202,10 @@ void Item_field::make_field(Send_field *tmp_field)
   DBUG_ASSERT(tmp_field->table_name != 0);
   if (name)
     tmp_field->col_name=name;			// Use user supplied name
+  if (table_name)
+    tmp_field->table_name= table_name;
+  if (db_name)
+    tmp_field->db_name= db_name;
 }