Hi XING, I appreciate your kindness. :-D Your detailed and prompt replies really helped me a lot. I will review the java doc you mentioned.
Best wishes, Trista Juan Pan [email protected] Juan Pan(Trista), Apache ShardingSphere On 09/29/2019 13:58，XING JIN<[email protected]> wrote： You can check the below doc of SqlValidatorUtil#getAlias for explanation: /** * Derives an alias for a node, and invents a mangled identifier if it * cannot. * * <p>Examples: * * <ul> * <li>Alias: "1 + 2 as foo" yields "foo" * <li>Identifier: "foo.bar.baz" yields "baz" * <li>Anything else yields "expr$<i>ordinal</i>" * </ul> * * @return An alias, if one can be derived; or a synthetic alias * "expr$<i>ordinal</i>" if ordinal < 0; otherwise null */ public static String getAlias(SqlNode node, int ordinal) But from my experience, you'd better not rely on above logic heavily. If you really care about the output name, just give it an alias explicitly. Juan Pan <[email protected]> 于2019年9月29日周日 下午1:27写道： That means Calcite can only return real columnName or columnLabel from simple column or alias. And any aggregate function, or calculate expression without alias, parsing expression, i.e, `EXPR$0` will be returned? Juan Pan [email protected] Juan Pan(Trista), Apache ShardingSphere On 09/29/2019 13:16，XING JIN<[email protected]> wrote： If no column name given explicitly, e.g. by alias or simple identifier, Calcite will derive one but not from the aggregate function. Juan Pan <[email protected]> 于2019年9月29日周日 下午1:12写道： Thank for your reply. It is a indirect way to get columnName. Calcite can not return the real columnName from SQL, is it right? Juan Pan [email protected] Juan Pan(Trista), Apache ShardingSphere On 09/29/2019 12:21，XING JIN<[email protected]> wrote： You can try to give an alias for the selected column. Juan Pan <[email protected]> 于2019年9月29日周日 上午11:39写道： Hi everyone, I executed SQL `select count(*) from tb1` through Calcite and resultSet.getMetaData().getColumnName(i) in my project. But the result is `EXPR$0` not `COUNT(*)`. Is there any way to get real columnName? Thanks for your attention. Regard, Trista Juan Pan [email protected] Juan Pan(Trista), Apache ShardingSphere
