Hi, I believe I've found a bug in the semantic analyzer (or maybe something else?). It occurs when using a column with a leading underscore in a subquery.
> create table temp (`_col` int, key int); > select key from temp; > select `_col` from temp; > select key from (select key from temp) t; The above queries all work fine. > select `_col` from (select `_col` from temp) t; > This query fails with "FAILED: Error in semantic analysis: line 1:7 Invalid Table Alias or Column Reference `_col`" The following query works in lieu of the above. > select col as `_col` from (select `_col` as col from temp) t; > Thanks, Marquis Wang HMC Computer Science '11