Gal reiketu dadeti salyga "InUseBy IS NULL" ?

"rl" <ask@me.for> wrote in message news:htl6se$vgm$1@trimpas.omnitel.net...
 UPDATE Jobs
 SET InUseBy = 'Jonas'
WHERE DateCreated = (SELECT MIN(DateCreated)
AND InUseBy IS NULL
FROM Jobs WHERE InUseBy IS  NULL)
>
> 1. Paleidi 2 tokius pacius update'us vienu metu
> 2. 1-as ivykdo (SELECT MIN(DateCreated) FROM Jobs WHERE InUseBy IS NULL). 
> Gauna DateCreated  reiksme
> 3. 2-as ivykdo (SELECT MIN(DateCreated) FROM Jobs WHERE InUseBy IS NULL) 
> gauna ta pacia DateCreated reiksme
> 4. 1-as uzsilockina update'inimui konkretu irasa
> 5. 2-as bando lockinti ta pati irasa ir laukia
> 6. 1-as pakeicia InUseBy = 'Jonas' ir paleidzia lock'a
> 7. 2-as uzsilockina irasa, pakeicia InUseBy = 'Petras' ir paleidzia.
>
> Galima situacija?