Ticks as primary key

[totoro]

I'm currently in the design phase of a new php/mySQL project.
I must build it with an abastraction layer, so that I can achieve database portability.

Thus I'm forbidden to use auto_increment of mySQL.

I've allready coded in VB.Net before, and the project architecht used "ticks" (10-6 secs since a certain date???) as primary keys for the tables.

Would this paractice be good in PHP also, and if yes, has anyone done it allready or know some documentation, I couldn't find anything relevant with google so far.

Thanx for any help people 😉

[drawmack]

I wouldn't do that as it could generate the same number twice. Personally I've never worked with a dbms that didn't have some way of doing autonumbers so you should be able to use that without the fear of non-portability.

[mrhappiness]

you might do something like

CREATE TABLE sequence(id INT PRIMARY KEY);

and

LOCK TABLES sequence WRITE;
SELECT MAX(id) + 1 FROM sequence;
INSERT INTO SEQUENCE SET id = MAX(id) + 1;
UNLOCK TABLES;

the value retrieved by the select can be used as primary key