Answer / uday

The best thing would be to create a trigger which checks and not allows duplicate data .

Create or replace trigger trig1
before insert or update on t1
for each row
declare
a number (10);
begin
select count(*) into a from t1 where col2 = :new.col2;
if a >= 1 then
raise_application_error(-20123,'data already present and data will not insert');
elsif a = 0 then
dbms_output.put_line('inserted');
end if;
end;

Answer / ravi gali

hi u can use DUP_VAL_ON_INDEX exception


SQL> create table test(id number primary key);



Table created.

SQL> set serverout on

SQL>

begin

insert into test values(1);

exception

when DUP_VAL_ON_INDEX then

raise_application_error('duplicate value entered on the row ');

when others then

dbms_output.put_line('if u entered wrong data');

end;

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