[predicates] use select_or_none rather than select+try/except, expected to be more efficient
fromyamsimportschema2sqlasy2sqldbhelper=repo.system_source.dbhelperrdefdef=schema['CWSource'].rdef('name')attrtype=y2sql.type_from_constraints(dbhelper,rdefdef.object,rdefdef.constraints).split()[0]cursor=session.cnxset['system']sql('UPDATE entities SET asource = source WHERE asource is NULL')dbhelper.change_col_type(cursor,'entities','asource',attrtype,False)dbhelper.change_col_type(cursor,'entities','source',attrtype,False)dbhelper.change_col_type(cursor,'deleted_entities','source',attrtype,False)