ID field for php script

hi all,

i have a db table with a field INT(4) UNSIGNED autoincrement named "person_ID".

The (4) attribute means that i can store up to 9999 values or not?

No. The (4) is just a display length. If there are less than 4 digits stored, and you are using zerofill, the number would be padded with zeros to four digits. You'll still be able to store a max unsigned value of 4,294,967,295.

i'm not using zerofill, my field is unsigned.

plase correct me if I'm wrong:

value: 156

field: int(4) unsigned zerofill > value becomes 0000156

field: int(4) unsigned > value is 156

field: smallint(1) unsigned zerofill > value becomes 0156

field: smallint(1) unsigned > value is 156

Right?

No, the length of an int(4) would be padded to a total length of 4 digits, so 156 would become 0156. The max value the field will hold isn't affected.

ok.

Last question: when i create a table can I omit the value between () or it is required?

It depends on the field type. Some require it, where others don't. Your best bet would to look at the manual for the field types, but if you omit one that's required, you should get an error returned to that effect.