SQL & PL/SQL

Howdy all. I am a somewhat beginner to Oracle, and I used the OMWB to migrate a MSSQL2K database to Oracle. I have a question about how to fill a variable with the results of a SELECT statement.

In T-SQL, the following is valid ...

----------------------------------

SELECT @ID = p.ID
FROM Persons p
WHERE Name = 'wally'

----------------------------------

This is valid and will not cause a runtime error for any number of rows returned (0 or more).


Now, for the Oracle looking equivalent ...

----------------------------------

SELECT ID
INTO ID
FROM PERSONS p
WHERE NAME = 'wally';

----------------------------------

I understand that this will throw a NO_DATA_FOUND exception if there are no rows in the result set or a TOO_MANY_ROWS exception if there are more than one rows in the result set.


However, the OMWB did the folliwing for all cases where the T-SQL looks like the above ...

----------------------------------

FOR rec IN (SELECT p.ID
FROM PERSONS p
WHERE p.NAME = 'wally')
LOOP
ID := rec.ID;
END LOOP;

----------------------------------


To my understanding, another way to write the same query would be ...

----------------------------------

SELECT ID
INTO ID
FROM PERSONS p
WHERE NAME = 'wally'
AND ROWNUM = 1;

----------------------------------


Ergo, my question. Is the LOOP method of filling the variable the same as the SELECT INTO method with the ROWNUM limiter? I realize that the SELECT INTO method must still handle the NO_DATA_FOUND exception. But, assuming there is at least one row in the result set without the ROWNUM limiter, will it that statement ever throw a NO_DATA_FOUND exception because of the ROWNUM limiter?

Any explanation would be appreciated.
wally