In most SQL conventions, single quotes are for Strings, while double quotes are for identifiers.
When I am running the following SQL in FLink 1.6.2, I got org.apache.calcite.sql.parser.impl.ParseException
from_unixtime(unix_timestamp(CREATE_TIME, 'EEE MMM dd HH:mm:ss zzz yyyy'),'yyyyMMdd'),
case when 1>= 10 and 1<= 21
) as date12
but when I use single quotes , such as ’02’ , it does not complain anything, it is a bit wired, because normally in SQL user can use double quotation or single quotation equally.
I want to know it is a Flink limitation or a bug? If it is a limitation, why?