以查询一个分区表的所有股票值为例：
ds=sqlDS(<select SecurityID from loadTable( "dfs://SH_TSDB_snapshot_MultiColumn", "snapshot") where date(DateTime)=2021.12.01>)
def disctcode(t){
return select distinct(SecurityID) as SecurityID from t
}
data = distinct(mr(ds, disctcode, ,unionAll{,false}).SecurityID)