create table my_table ( a number , b varchar2(10) constraint b_chk check (instr(b,'%')=0) )
;
Table created

exec dbms_errlog.create_error_log( 'my_table', 'my_table_ERR' );
PL/SQL procedure successfully completed

insert into my_table(a,b)
select rownum, 'val'||rownum||case mod(rownum,3) when 0 then '%' end
from dual connect by level < 10
log errors into my_table_ERR
 REJECT LIMIT unlimited
;
6 rows inserted

select * from my_table;
    A B
----- -----
    1 val1
    2 val2
    4 val4
    5 val5
    7 val7
    8 val8
6 rows selected

select a,b,ORA_ERR_NUMBER$ from my_table_err;
A     B     ORA_ERR_NUMBER$
----- ----- ---------------
3     val3%            2290
6     val6%            2290
9     val9%            2290

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