ID incrementing for multiple users - please help

[eluser]Alexxz[/eluser]
Be careful.

Code:

select nextID from thirdtable;
update thirdtable set nextID = nextID + 1;

This must be in transaction. Or another method to except this

Code:

1> select nextID from thirdtable;
2> select nextID from thirdtable;
1> update thirdtable set nextID = nextID + 1;
2> update thirdtable set nextID = nextID + 1;