On 13-Jul-01 David Bouw wrote:
<snipage ahead>
>
> Something that I noticed was that you could also add an option to say if a
> Int was unsigned ot signed..
>
> Does it have any sence to use a signed int on a autoincrement table..?
> E.g. When using a auto-increment correctly you will never need a negative
> number..
I don't think there's ever a reason for a negative id#
(who lives in Apt -12; or has driver license -91678 ?).
> Do I need to do an optimize on a table when changing this from signed to
> unsigned..?
>
Wouldn't think so.
>
> An Int is 4 bytes and a Medium Int is 3 bytes.. Can you roughtly say dat a
> Medium Int is 33% faster when doing queries
It "could" be 33% smaller on disk, but not necessarily any faster.
> Do I throw away a lof of speed when grabbing a integer which probably is to
> large for me..?
>
No, just (possible) disk space.
> What I also noticed is that you can add a 'length' tag to a integer. Why is
> this, why would you want to make the length shorter than
> the
> integer type permits..?
>
The server pads the field to the length parameter.
This makes for consistent looking displays on interface(s) that don't have
formatting tools:
[ id int(11) ]
mysql> select * from crossref where id <200;
+--------+-----+
| word | id |
+--------+-----+
| foobaz | 12 |
| foobar | 1 |
| foobar | 99 |
| foobar | 187 |
| foofoo | 8 |
+--------+-----+
mysql> select * from crossref where id <20;
+--------+----+
| word | id |
+--------+----+
| foobar | 1 |
| foofoo | 8 |
| foobaz | 12 |
+--------+----+
^ ------------^
^ -------------^ --- note the differing widths
[now id int(3)]
mysql> select * from crossref where id <200;
+--------+------+
| word | id |
+--------+------+
| foobar | 1 |
| foofoo | 8 |
| foobaz | 12 |
| foobar | 99 |
| foobar | 187 |
+--------+------+
mysql> select * from crossref where id <20;
+--------+------+
| word | id |
+--------+------+
| foobar | 1 |
| foofoo | 8 |
| foobaz | 12 |
+--------+------+
'course your app can do whatever.
Regards,
--
Don Read [EMAIL PROTECTED]
-- It's always darkest before the dawn. So if you are going to
steal the neighbor's newspaper, that's the time to do it.
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