No_data_found exception is propagating to outer block also? - sql

Question

In my code i am entering the salary which is not available in employees table and then again inserting duplicate employee_id in primary key column of employee table in exception block where i am handling no data found exception but i do not why No data found exception in the end also?
OUTPUT coming:
Enter some other sal
ORA-01400: cannot insert NULL into ("SCOTT"."EMPLOYEES"."LAST_NAME")
ORA-01403: no data found --This should not come according to logic
This is the code:
DECLARE
v_sal number:=&p_sal;
v_num number;
BEGIN
BEGIN
select salary INTO v_num from employees where salary=v_sal;
EXCEPTION
WHEN no_data_found THEN
DBMS_OUTPUT.PUT_LINE('Enter some other sal');
INSERT INTO employees (employee_id)values(100) ;
END;
EXCEPTION
WHEN OTHERS THEN
DBMS_OUTPUT.PUT_LINE(sqlerrm);
END;

Answer 1

The behaviour is that errors hurled in the EXCEPTIONS block get concatenated to SQLERRM, and hence propagated upwards. I grant you it is not documented but we can clearly see it here:
SQL> declare
2 v_sal t23.sal%type := 230;
3 l_num t23.sal%type;
4 begin
5 begin
6 begin
7 select sal into l_num
8 from t23 where sal = v_sal;
9 exception
10 when no_data_found then
11 dbms_output.put_line('inner exception::'||sqlerrm);
12 insert into t23 values (99, 'MR KNOX', v_sal);
13 end;
14 exception
15 when dup_val_on_index then
16 dbms_output.put_line('middle exception::'||sqlerrm);
17 insert into t23 (id, sal) values (99, v_sal);
18 end;
19 exception
20 when others then
21 dbms_output.put_line('outer exception::'||sqlerrm);
22 end;
23 /
inner exception::ORA-01403: no data found
middle exception::ORA-00001: unique constraint (APC.T23_PK) violated
ORA-01403: no data found
outer exception::ORA-01400: cannot insert NULL into ("APC"."T23"."LAST_NAME")
ORA-00001: unique constraint (APC.T23_PK) violated
ORA-01403: no data found
PL/SQL procedure successfully completed.
SQL>
Note: if there is a nested exception block which successfully handles the thrown exception it is not concatenated to SQLERRM. That is, the SQLERRM consists of a stack of unsucessfully handled exceptions.

Answer 2

In your exception block you try to insert into employees, but do not set the column last_name, which is not NULL-able.
ORA-01400: cannot insert NULL into ("SCOTT"."EMPLOYEES"."LAST_NAME")
The ORA-01403: no data found is part of the stack-trace, caused by your failed select.
You can either define DEFAULT values for all not-nullable columns or change your insert:
INSERT INTO employees (employee_id, last_name, ...) Values (100, 'Scott', ...);