"lister" <listerofsmeg01@hotmail.com> wrote in message
news:1189712056.128679.217400@22g2000hsm.googlegro ups.com...
> Hi all,
>
> I have a table where I need entries to be unique across two columns.
> ie:
>
> NAME UNIQUE
> john true
> john false
> john false
>
> I can have as many john false's as I like, but only ever one john
> true.
>
> I need to prevent two people inserting a john true at the same time.
> As far as I can see, the unique contraint can only be applied to a
> single column so I can't use the built in stuff.
>
> It appears to my newbie eyes that the only way I can do this is with a
> table write lock. ie:
> Lock the table for writes
> Do a SELECT to see if the unique entry is already in there.
> Insert it if it isn't
> Unlock the table.
>
> Are there any quicker / more efficient ways? Also I'm a bit unsure of
> the syntax to only insert if the select comes up empty. Can anyone
> point me in the right direction?
>
> Many thanks,
> Lister
>

What version of MySQL are you using?

Evan