I was stumbling upon...

I was “stumbling upon” and hit this site. It reminded me of my all time favorite “oh, I wish it didn’t work that like” things in PLSQL.

SQL> create table t ( x int );
Table created.

SQL> begin
2          for i in 1 .. 2
3          loop
4                  insert into t values ( i );
5          end loop
6          rollback;
7  end;
8  /
PL/SQL procedure successfully completed.

SQL> select * from t;

       X
----------
       1
       2

Neat, eh? The first C thing written on that page with the comment reminded me of it, a similar issue.

PLSQL has the same issue as C with the comment though (as would many/most languages I think)

SQL> declare
2          a number := 1;
3          b number := 2;
4          c number := 3;
5          d number := 4;
6  begin
7          a := b; /* this is a bug
8          c := d; /* c=d will never happen */
9          dbms_output.put_line( 'D = ' || d );
10          dbms_output.put_line( 'C = ' || c );
11  end;
12  /
D = 4
C = 3
PL/SQL procedure successfully completed.

#7 on that referenced page on C reminds me lots of zero divide issues people have:

SQL> create table t ( x int, y int );
Table created.

SQL> insert into t values ( 1, 0 );
1 row created.

SQL> select /*+ RULE */ * from t where y > 0 and x/y > 0;
select /*+ RULE */ * from t where y > 0 and x/y > 0
                                           *
ERROR at line 1:
ORA-01476: divisor is equal to zero


SQL> select /*+ RULE */ * from t where x/y > 0 and y > 0;
no rows selected

But best of all about that page? It is a top 10 with 17 things… I liked that as my top 5 things done wrong presentation now has 7 things in it (and I never have changed the title…)