Another choice is just like you said, you can add Date as UDF but because Date is a reserved word, you may need to quote the function name like `Date`(col1) based on what quoting character you use.
Andrew O <[email protected]> 于2019年6月6日周四 下午7:07写道： > I'm doing a project trying to parse some IBM DB2 sql expressions (to > analyze table / column usages). > > To note, > 1) these are existing ad-hoc user queries so I can't change their syntax > 2) I don't have a connection / schema for the database, but my > understanding is that this shouldn't be required by Calcite for this > kind of work. > > Currently I'm hitting some parsing issues with queries like > > select Date(x.col1), x.col2 from myTable x > > It fails parse at the point of the Date function call. This is trying to > use the function to convert the value of col1 to a date (almost similar to > a cast/convert). > > > https://www.ibm.com/support/knowledgecenter/en/SSEPEK_11.0.0/sqlref/src/tpc/db2z_bif_date.html > > > My current thinking would be that this may need changes to the parser > grammar (through an extension?). Or perhaps this could be registered as a > custom User Defined Function of some kind (although Date seems like a > reserved word)? > > Is this the right thinking, or is there another approach I could look at? > > Thanks in advance > > Andrew >
