Question

This is how I am delcaring the local variables:

   team_counter number (38) := 0;
   username varchar2(50) := '';

This is how I am trying to use/see their value after using some select into statement:

    dbms_output.put_line(team_counter||'.'||username);
    if  team_counter< 30 AND username  <>'' then
    begin
        dbms_output.put_line('yuhj');
    end;
    end if;

The second output is not being printed!
The first output is being printed as ‘1.tuser’ which I was expecting.

Answer 1

This is because you’re trying to compare a string with a 0 length string using an inequality operator.

Oracle assumes that 0 length strings are equivalent to NULL and will not evaluate comparisons that don’t use the NULL specific conditional. To quote:

Oracle Database currently treats a character value with a length of
zero as null. However, this may not continue to be true in future
releases, and Oracle recommends that you do not treat empty strings
the same as nulls.

Simply put this means that your IF statement should be:

if team_counter < 30 and username is not null then
   ...

As an additional note there’s no need for the begin ... end around the dbms_output.put_line. As you’re not catching any exceptions explicitly related to this call or declaring additional variables etc there’s no real need.