delete from student where name = 'xiyanmao';
insert into cb_dmatnr (A,B,C)
select 'A','A','A' from dual
union
select 'B,'B','B' from dual
delete from student where name = 'xiyanmao';
insert into cb_dmatnr (A,B,C)
select 'A','A','A' from dual
union
select 'B,'B','B' from dual