SQL> create table index_test(id number ,name varchar2(30) ,PRIMARY KEY(ID,NAME)) ;

Table created.

执行下面的语句时,哪句会报错

SQL1> insert into index_test values(2,'');

SQL2> insert into index_test values(3,'a');

SQL3> insert into index_test values(3,null);

SQL4> insert into index_test values(3,'a');

执行下面的语句时,哪句会报错？