MDEV-16473 WITH statement throws 'no database selected' error

Different fix, just use NULL, not no_db,

sql/sql_class.h

@@ -3959,12 +3959,9 @@ public:
         my_message(ER_NO_DB_ERROR, ER(ER_NO_DB_ERROR), MYF(0));
         return TRUE;
       }
-      /*
-        It does not matter what database name is set in this case
-        because it will never be used after parser stage
-      */
-      *p_db_length= strlen(no_db);
-      *p_db= strmake(no_db, *p_db_length);
+      /* This will allow to throw an error later for non-CTE references */
+      *p_db= NULL;
+      *p_db_length= 0;
     }
     else
     {