[mythtv-users] UK DVB-T Duplicates usually on Dave, Sky3 etc... how to remove?

Ian Clark mrrooster at gmail.com
Fri Jun 6 14:27:39 UTC 2008


2008/6/6 Mike Holden <mythtv at mikeholden.org>:

> Nick Morrott wrote:
> <snip>
>


> ... In Oracle, an empty string is equivalent to
> null.
>

Well, that's good to know!! (So, that's why people swear about Oracle).

>
> I don't know if mysql works this way as well, but it would explain the
> issue we are seeing if the code is testing for equality between 2 empty
> string values if it does work the same way as Oracle.


It would appear this isn't true in MySQL.

mysql> select count(*) FROM users WHERE ''='';
+----------+
| count(*) |
+----------+
|       17 |
+----------+
1 row in set (0.00 sec)

mysql> select count(*) FROM users WHERE NULL=NULL;
+----------+
| count(*) |
+----------+
|        0 |
+----------+
1 row in set (0.00 sec)

mysql> select count(*) FROM users WHERE NULL IS NULL;
+----------+
| count(*) |
+----------+
|       17 |
+----------+
1 row in set (0.00 sec)

mysql>

Infact... that's really f'd up! It's almost as annoying as Sybase treating '
' and '' as the same thing. (although that's a setting which can be changed
in later versions.)

I
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