Re: one value from one of three different tables

[Peter Brawley]

I'm not clear about that design. For example, doesn't a flock's history ever need to be tracked? If so, you might want something more like ...

locations( locID smallint unsigned primary key auto_increment, 
           name, 
           stage enum('incubation','barn','pen'), 
           capacity, ... )

flock( flockID smallint unsigned primary key auto_increment, name, size, ... )

flockhist( histID smallint unsigned primary key auto_increment, 
           flockID smallint unsigned, 
           stage enum('incubation','barn','pen'), 
           locationID smallint unsigned, 
           indate date outdate date, 
           foreign key(locationID) references locations(locID) ... )