Only one expression can be specified in the select list when the subquery is not introduced with EXI
/*错误的*/selectsong.song_name,song.title_url,song.mv_url,singer.singer_namefromWEBDB_PROD_SONGassong,WEBDB_PROD_SINGERassingerwheresong.singer_id=singer.singer_idandsong.song_name=(select*fromWEBDB_PROD