Re: Theoretical Basis for SELECT FOR UPDATE
From: Tony Andrews <andrewst_at_onetel.com>
Date: 4 Oct 2005 12:54:35 -0700
Message-ID: <1128455675.682745.164260_at_g43g2000cwa.googlegroups.com>
Date: 4 Oct 2005 12:54:35 -0700
Message-ID: <1128455675.682745.164260_at_g43g2000cwa.googlegroups.com>
vc wrote:
> Assuming t1 contains one row, consider this:
>
> update t1 set x=2, update t1 set x=3;
>
> Wha(and why) will the result be, two or three, or unpredictable ?
If it were allowed, it would be unpredictable. But it should not be allowed, because it attempts to do two contradictory things at once.
What should happen in SQL if you do this (equivalent) statement?:
update t1 set x=2, x=3;