达梦数据库SQL，梦数据库sql

达梦数据库SQL，梦数据库sql

SUBSTRING()函数

select * , substring(SONG_ID from 3) from TBL_SONG where SONG_ID like '11__';

例如select * ,'04'+substring("DBNAME"."SCHAMENAME"."TABLENAME"."INDEX_ID" from 3 )

from  "DBNAME"."SCHAMENAME"."TABLENAME"."INDEX_ID"  like '11___';

rownum(可以利用rownum实现数据库记录去重)

select * from TBL_SONG where rownum in (select a.rownum from (select distinct SONG_ID, rownum from TBL_SONG) as a ) as b;

或者delete from TBL_SONG where rownum not in (select a.rownum from (select distinct SONG_ID, rownum from TBL_SONG) as a ) as b;